Expertiza_Wiki - User contributions [en]

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-11-06T02:46:15Z

Ajoshi5: /* Code Cleanup */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==
The StudentQuiz controller consists of methods involved in creating, scoring & recording responses of the quizzes taken by reviewers or students of the other teams with the same topic.
 The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Follow principle of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view. This is illustrated well in the example mentioned above for the [http://wiki.expertiza.ncsu.edu/index.php/CSC/ECE_517_Fall_2014/oss_E1460_aua#RESTful_style_implementation RESTful style implementation].

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database. By doing this, we followed the Single Responsibility O-O Design Principle for methods mentioned by Mr. Robert C. Martin which states that "Every software module should have only one reason to change"<ref>[http://www.codeproject.com/Articles/567768/Object-Oriented-Design-Principles O-O Design Principles]</ref>
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
questionnaire = Questionnaire.find(map.reviewed_object_id)
scores = Array.new
valid = true
questions = Question.where(questionnaire_id: questionnaire.id)
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|

correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

end
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

end
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
scores.each do |score_update|
score_update.score = score
end
end
else
correct_answer = correct_answers.first
if ques_type.eql? 'Essay'
score = -1
elsif correct_answer && params["#{question.id}"]== correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => response.id, :score => score
if new_score.comments.empty? || new_score.comments.nil?
valid = false
end
scores.push(new_score)
end
end
if valid
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => questionnaire.id
end
end
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-11-05T15:36:53Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==
The StudentQuiz controller consists of methods involved in creating, scoring & recording responses of the quizzes taken by reviewers or students of the other teams with the same topic.
 The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Follow principle of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database. By doing this, we followed the Single Responsibility O-O Design Principle for methods mentioned by Mr. Robert C. Martin which states that "Every software module should have only one reason to change"<ref>[http://www.codeproject.com/Articles/567768/Object-Oriented-Design-Principles O-O Design Principles]</ref>
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
questionnaire = Questionnaire.find(map.reviewed_object_id)
scores = Array.new
valid = true
questions = Question.where(questionnaire_id: questionnaire.id)
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|

correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

end
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

end
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
scores.each do |score_update|
score_update.score = score
end
end
else
correct_answer = correct_answers.first
if ques_type.eql? 'Essay'
score = -1
elsif correct_answer && params["#{question.id}"]== correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => response.id, :score => score
if new_score.comments.empty? || new_score.comments.nil?
valid = false
end
scores.push(new_score)
end
end
if valid
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => questionnaire.id
end
end
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-11-05T15:31:51Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==
The StudentQuiz controller consists of methods involved in creating, scoring & recording responses of the quizzes taken by reviewers or students of the other teams with the same topic.
 The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Follow principle of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database. By doing this, we followed the Single Responsibility O-O Design Principle for methods which states that "Every software module should have only one reason to change"<ref>[http://www.codeproject.com/Articles/567768/Object-Oriented-Design-Principles O-O Design Principles]</ref>
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
questionnaire = Questionnaire.find(map.reviewed_object_id)
scores = Array.new
valid = true
questions = Question.where(questionnaire_id: questionnaire.id)
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|

correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

end
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

end
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
scores.each do |score_update|
score_update.score = score
end
end
else
correct_answer = correct_answers.first
if ques_type.eql? 'Essay'
score = -1
elsif correct_answer && params["#{question.id}"]== correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => response.id, :score => score
if new_score.comments.empty? || new_score.comments.nil?
valid = false
end
scores.push(new_score)
end
end
if valid
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => questionnaire.id
end
end
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-11-05T15:28:57Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==
The StudentQuiz controller consists of methods involved in creating, scoring & recording responses of the quizzes taken by reviewers or students of the other teams with the same topic.
 The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Follow principle of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database. By doing this, we followed the Single Responsibility O-O Design Principle for methods which states that "Every software module should have only one reason to change"<ref>http://www.codeproject.com/Articles/567768/Object-Oriented-Design-Principles</ref>
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
questionnaire = Questionnaire.find(map.reviewed_object_id)
scores = Array.new
valid = true
questions = Question.where(questionnaire_id: questionnaire.id)
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|

correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

end
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

end
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
scores.each do |score_update|
score_update.score = score
end
end
else
correct_answer = correct_answers.first
if ques_type.eql? 'Essay'
score = -1
elsif correct_answer && params["#{question.id}"]== correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => response.id, :score => score
if new_score.comments.empty? || new_score.comments.nil?
valid = false
end
scores.push(new_score)
end
end
if valid
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => questionnaire.id
end
end
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T01:15:15Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
questionnaire = Questionnaire.find(map.reviewed_object_id)
scores = Array.new
valid = true
questions = Question.where(questionnaire_id: questionnaire.id)
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|

correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

end
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

end
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
scores.each do |score_update|
score_update.score = score
end
end
else
correct_answer = correct_answers.first
if ques_type.eql? 'Essay'
score = -1
elsif correct_answer && params["#{question.id}"]== correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => response.id, :score => score
if new_score.comments.empty? || new_score.comments.nil?
valid = false
end
scores.push(new_score)
end
end
if valid
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => questionnaire.id
end
end
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T01:11:10Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:48:27Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores array contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:41:44Z

Ajoshi5: /* Changes made in method logic */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:38:43Z

Ajoshi5: /* Replace controller method with a model method */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method : index
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:35:47Z

Ajoshi5: /* Replace controller method with a model method */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the database.
The code was extracted into the get_mappings_for_reviewer method and placed in the file quiz_response_map.rb. This method was then called from the StudentQuizzes controller.
<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models Fat Models and Skinny Controllers.]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method :
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>
 quiz_response_map.rb
<pre>
def self.get_mappings_for_reviewer(participant_id)
return QuizResponseMap.where(reviewer_id: participant_id)
end
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:11:48Z

Ajoshi5: /* Use of Routing Helpers */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code. Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:11:02Z

Ajoshi5: /* Use good conditional statements */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition. Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:10:18Z

Ajoshi5: /* Use good conditional statements */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:08:09Z

Ajoshi5: /* Used a Boolean variable when that is sufficient */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:06:43Z

Ajoshi5: /* Used a Boolean variable when that is sufficient */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:05:57Z

Ajoshi5: /* Used .nil? instead of "== nil" */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:05:30Z

Ajoshi5: /* Used .nil? instead of "== nil" */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
Before Refactoring
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:04:31Z

Ajoshi5: /* Replace find_by_... with a where command */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
 Before Refactoring 
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:03:27Z

Ajoshi5: /* Use key: ‘value’, not :key => ‘value’ */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:01:37Z

Ajoshi5: /* Use `&&` and `||` rather than `and` and `or` to keep boolean precedence */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-29T00:00:26Z

Ajoshi5: /* Eliminated the "== true/false" check */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:59:53Z

Ajoshi5: /* Used .eql? instead of "==" */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:58:09Z

Ajoshi5: /* Code Cleanup */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
Method : list
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:55:58Z

Ajoshi5: /* Pluralized the class name StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:53:47Z

Ajoshi5: /* Elimination of Boolean Zen */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
 Method : graded?
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:53:02Z

Ajoshi5: /* Elimination of Boolean Zen */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
Method : graded?
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:50:13Z

Ajoshi5: /* Instance Variable Reductions */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:42:18Z

Ajoshi5: /* RESTful style implementation */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 Method : list
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :
 Method : index
<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:30:40Z

Ajoshi5: /* Project Description */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods.</li>
<li>Fix logical errors in the code.</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:28:46Z

Ajoshi5: /* Project Description */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class. (StudentQuizzesController)</li>
<li>Rename methods to conform to RESTful style. (e.g. :- Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Perform Code cleanup by removing unused code.</li>
<li>Use good Ruby style guidelines in the code.</li>
<li>Split a method performing multiple tasks, into seperate methods</li>
<li>Fix logical errors in the code</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:24:43Z

Ajoshi5: /* Project Description */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T23:21:37Z

Ajoshi5: /* Expertiza - Refactoring StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the StudentQuiz controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:25:18Z

Ajoshi5: /* Modification to Existing Code */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modifications made to the Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:24:32Z

Ajoshi5: /* Pluralized the class name StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
----
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:24:18Z

Ajoshi5: /* RESTful style implementation */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
----
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:15:04Z

Ajoshi5: /* Replace controller method with a model method */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

===Replace controller method with a model method ===
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:06:35Z

Ajoshi5: /* Elimination of Boolean Zen */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>[https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf About Boolean Zen]</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:05:52Z

Ajoshi5: /* Instance Variable Reductions */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>[http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages Disadvantages of Tight Coupling - Wikipedia]</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

----
* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

----
* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

----
* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

----
* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

----
* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:04:36Z

Ajoshi5: /* Instance Variable Reductions */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them <ref>[http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability Decreasing Controller-View Coupling in Rails]</ref>. Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
----
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
----
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:02:46Z

Ajoshi5: /* Pluralized the class name StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>[http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails Using the Singular or Plural controller and helper names in Rails]</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
----
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
----
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
----
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
----
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:01:36Z

Ajoshi5: /* Project Description */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our project requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
---
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T21:01:08Z

Ajoshi5: /* Project Description */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>[https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit# GoogleDoc for our assignment requirements]</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====
----
Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
----
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:59:27Z

Ajoshi5: /* Expertiza - Refactoring StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>[http://wikis.lib.ncsu.edu/index.php/Expertiza Expertiza Wiki Page]</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
----
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:58:47Z

Ajoshi5: /* Expertiza - Refactoring StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>[https://github.com/expertiza/expertiza Expertiza on GitHub]</ref><ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
----
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
----
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
----
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
--
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:56:05Z

Ajoshi5: /* Expertiza - Refactoring StudentQuizController */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)[https://github.com/expertiza/expertiza Expertiza on GitHub]<ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:

Before Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
@quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
@assignment = Assignment.find(assignment_id)
teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
if !@assignment.team_assignment?
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
@quizzes.push(questionnaire)
end
else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
@quizzes.push(questionnaire)
end
end
end
end
end
return @quizzes
end
</pre>

After Refactoring
<pre>
def self.take_quiz assignment_id , reviewer_id
quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
quizzes.push(questionnaire)
end
end
end
end
return quizzes
end
</pre>

===Elimination of Boolean Zen===
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:47:21Z

Ajoshi5: /* Code Cleanup */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>https://github.com/expertiza/expertiza</ref><ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

Before Refactoring

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:
<pre>
def self.take_quiz assignment_id , reviewer_id
- @quizzes = Array.new
+ quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
- @assignment = Assignment.find(assignment_id)
- teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
- if !@assignment.team_assignment?
- unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
- @quizzes.push(questionnaire)
- end
- else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
- @quizzes.push(questionnaire)
+ unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
+ quizzes.push(questionnaire)
end
end
end
end
+ return quizzes
end
- return @quizzes
-end
</pre>

===Elimination of Boolean Zen===
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Following Ruby Style Guidelines (Global Rules)===
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:46:02Z

Ajoshi5: /* Following Ruby Style Guidelines (Global Rules) */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>https://github.com/expertiza/expertiza</ref><ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

Before Refactoring

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:
<pre>
def self.take_quiz assignment_id , reviewer_id
- @quizzes = Array.new
+ quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
- @assignment = Assignment.find(assignment_id)
- teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
- if !@assignment.team_assignment?
- unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
- @quizzes.push(questionnaire)
- end
- else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
- @quizzes.push(questionnaire)
+ unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
+ quizzes.push(questionnaire)
end
end
end
end
+ return quizzes
end
- return @quizzes
-end
</pre>

===Elimination of Boolean Zen===
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

*Modified declarations of Arrays and Hashes
Before Refactoring :
<pre>

</pre>

After Refactoring :
<pre>

</pre>

*Removed unused methods like self.participants_in and commented out code.

===Following Ruby Style Guidelines (Global Rules)===
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:37:21Z

Ajoshi5: /* Replace controller method with a model method */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>https://github.com/expertiza/expertiza</ref><ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

Before Refactoring

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:
<pre>
def self.take_quiz assignment_id , reviewer_id
- @quizzes = Array.new
+ quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
- @assignment = Assignment.find(assignment_id)
- teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
- if !@assignment.team_assignment?
- unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
- @quizzes.push(questionnaire)
- end
- else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
- @quizzes.push(questionnaire)
+ unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
+ quizzes.push(questionnaire)
end
end
end
end
+ return quizzes
end
- return @quizzes
-end
</pre>

===Elimination of Boolean Zen===
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

*Modified declarations of Arrays and Hashes
Before Refactoring :
<pre>

</pre>

After Refactoring :
<pre>

</pre>

*Removed unused methods like self.participants_in and commented out code.

===Following Ruby Style Guidelines (Global Rules)===
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Method names should use underscores, not camelcase. ====

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Use good array checking====

[].empty? # not [].length == 0 or [].length.zero?
[:foo].any? # not [:foo].length > 0
[:foo].one? # not [:foo].length == 1
[:foo].first # not [:foo][0]
[:foo].last # not [:foo][-1]

====Use find_each for efficient loops over models====

SignedUpUser.all.each do |user| # BAD
SignedUpUser.find_each do |user| # GOOD

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quizzes_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:32:11Z

Ajoshi5: /* Instance Variable Reductions */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>https://github.com/expertiza/expertiza</ref><ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables that are not used in the views.

Before Refactoring

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:
<pre>
def self.take_quiz assignment_id , reviewer_id
- @quizzes = Array.new
+ quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
- @assignment = Assignment.find(assignment_id)
- teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
- if !@assignment.team_assignment?
- unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
- @quizzes.push(questionnaire)
- end
- else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
- @quizzes.push(questionnaire)
+ unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
+ quizzes.push(questionnaire)
end
end
end
end
+ return quizzes
end
- return @quizzes
-end
</pre>

===Elimination of Boolean Zen===
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

*Modified declarations of Arrays and Hashes
Before Refactoring :
<pre>

</pre>

After Refactoring :
<pre>

</pre>

*Removed unused methods like self.participants_in and commented out code.

===Following Ruby Style Guidelines (Global Rules)===
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Method names should use underscores, not camelcase. ====

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Use good array checking====

[].empty? # not [].length == 0 or [].length.zero?
[:foo].any? # not [:foo].length > 0
[:foo].one? # not [:foo].length == 1
[:foo].first # not [:foo][0]
[:foo].last # not [:foo][-1]

====Use find_each for efficient loops over models====

SignedUpUser.all.each do |user| # BAD
SignedUpUser.find_each do |user| # GOOD

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quiz_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>

CSC/ECE 517 Fall 2014/oss E1460 aua

2014-10-28T20:31:54Z

Ajoshi5: /* Instance Variable Reductions */

==Expertiza - Refactoring StudentQuizController==
Expertiza is a web application developed using Ruby on Rails that serves as a peer-review system. The application allows students to submit and peer-review learning objects (articles, code, web sites, etc)<ref>https://github.com/expertiza/expertiza</ref><ref>http://wikis.lib.ncsu.edu/index.php/Expertiza</ref>. It is an open source project and it's codebase is maintained in GitHub. We are contributing to Expertiza as a part of our Object-Oriented Design and Development's Open-Source Software (OSS) Project. Our goal in this project is to refactor the Student Quiz Controller. In this Wiki Page, we would be explaining the changes that we have made for the same.
__TOC__

==Project Description==

Our Goal in this project is to refactor the StudentQuiz controller. This class records the quizzes that the student has attempted and its progress and also submits grades for the essays in the quizzes attempted by the student. The changes that are needed to be done are described as follows:<ref>https://docs.google.com/a/ncsu.edu/document/d/1FZCL9KWSdVNsX9BowuZ3gxbCOJoiWX-GVLctSZei3No/edit#</ref>
<ol>
<li>Pluralize the class (StudentQuizzesController).</li>
<li>Rename methods to conform to RESTful style (Rename the list method to index.)</li>
<li>Reduce the number of instance variables per controller action.</li>
<li>Review Method graded? for boolean zen.</li>
<li>Performing Code cleanup by removing unused code.</li>
<li>Using good Ruby style guidelines in the code.</li>
<li>Splitting a method performing multiple tasks, into seperate methods</li>
<li>Fixing logical errors in the code</li>
</ol>

==Modification to Existing Code==

===Pluralized the class name StudentQuizController===
As per the Rails convention the controller class names are suggested to be plural.
This helps in generating RESTful routing URI helpers. Also, naming the classes as plural seems intuitive.<ref>http://stackoverflow.com/questions/646951/singular-or-plural-controller-and-helper-names-in-rails</ref>.
We used the refactor functionality in RubyMine to rename the StudentQuiz controller class to StudentQuizzes.

The following files were modified and/or renamed.
<pre>
app/controllers/review_mapping_controller.rb
app/controllers/{student_quiz_controller.rb → student_quizzes_controller.rb}
app/helpers/student_quiz_helper.rb
app/helpers/student_quizzes_helper.rb
app/views/questionnaires/view.html.erb
app/views/{student_quiz → student_quizzes}/_quiz_form.html.erb
app/views/{student_quiz → student_quizzes}/_responses.html.erb
app/views/{student_quiz → student_quizzes}/_set_dynamic_quiz.html.erb
app/views/{student_quiz → student_quizzes}/_set_self_quiz.html.erb
app/views/{student_quiz → student_quizzes}/finished_quiz.html.erb
app/views/{student_quiz → student_quizzes}/grade_essays.html.erb
app/views/{student_quiz → student_quizzes}/list.html.erb
app/views/{student_quiz → student_quizzes}/take_quiz.html.erb
app/views/student_task/view.html.erb
app/views/tree_display/actions/_assignments_actions.html.erb
test/functional/{student_quiz_controller_test.rb → student_quizzes_controller_test.rb}
test/test_helper.rb
test/unit/helpers/student_quiz_helper_test.rb
test/unit/helpers/student_quizzes_helper_test.rb
</pre>

The detailed change-set for this refactor can be seen [https://github.com/ankit3005/expertiza/commit/20981333a14a3f468f76cd6d414b3088975b71bd here].

===RESTful style implementation===
The purpose of the list method in the StudentQuizzes controller is to list all the quizzes that are available to a particular user for a particular assignment. RESTful guidelines state that a method that returns a list of all available objects, in this case the quizzes, should be named as index. Therefore, we renamed the list method to the index method in the controller and in all the files that had references to the list method of the student_quizzes_controller (For e.g. :- The view finished_quiz.html.erb of the Student Quiz controller, the review_mapping controller.rb etc.).

Before Refactoring :
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring :

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

===Instance Variable Reductions===
In Rails, the data is shared between the controllers and views through the instance variables. The instance variabIes that are set during the execution a particular controller method are accessible to the view. Excessive usage of this standard method of data sharing between the controller and the view results in increased coupling between them. <ref>http://blog.remarkablelabs.com/2013/01/how-to-decrease-coupling-in-your-controllers-views-with-decent_exposure-for-better-maintainability</ref> Increased coupling results in several problems, including less maintainability of code, difficulty in code reuse etc. <ref>http://en.wikipedia.org/wiki/Coupling_(computer_programming)#Disadvantages</ref> Thus, we need to reduce coupling as much as possible and in this case it can be achieved by reducing as many instance variables as possible in the controller. Therefore, we have refactored our code in order to eliminate unnecessary instance variables and to convert all the instance variables to local variables if they are not used in the views.

Before Refactoring

student_quizzes_controller.rb

In the take_quiz method, the following instance variables were removed:
 
* Changed the quizzes instance variable to a local variable.
* Eliminated the instance variable assignment which was not being used anywhere.
* Eliminated the local variable teams which was not being used any where
The unified diff of the changes made is shown below:
<pre>
def self.take_quiz assignment_id , reviewer_id
- @quizzes = Array.new
+ quizzes = Array.new
reviewer = Participant.where(user_id: reviewer_id, parent_id: assignment_id).first
- @assignment = Assignment.find(assignment_id)
- teams = TeamsUser.where(user_id: reviewer_id)
Team.where(parent_id: assignment_id).each do |quiz_creator|
unless TeamsUser.find_by_team_id(quiz_creator.id).user_id == reviewer_id
Questionnaire.where(instructor_id: quiz_creator.id).each do |questionnaire|
- if !@assignment.team_assignment?
- unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
- @quizzes.push(questionnaire)
- end
- else unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer_id).first
- @quizzes.push(questionnaire)
+ unless QuizResponseMap.where(reviewed_object_id: questionnaire.id, reviewer_id: reviewer.id).first
+ quizzes.push(questionnaire)
end
end
end
end
+ return quizzes
end
- return @quizzes
-end
</pre>

===Elimination of Boolean Zen===
In cases where a method only returns a boolean value by evaluating an expression (using the if..else construct), the if..else statement is redundant and can be eliminated. We have a method graded? that does this thing. Thus, we eliminated the if..else construct in the graded? method as it was redundant.<ref>https://www.cs.utexas.edu/~scottm/cs312/handouts/slides/topic16_boolean_logic.pdf</ref>

 Before Refactoring 
 
student_quizzes_controller.rb
 
<pre>
def graded?(response, question)
if Score.where(question_id: question.id, response_id: response.id).first
return true
else
return false
end
end
</pre>

 After Refactoring 
<pre>
def graded?(response, question)
return (Score.where(question_id: question.id, response_id: response.id).first)
end
</pre>

===Code Cleanup===
At some places, we found certain statements and variable assignments that were not being used later on in the method or code. We have eliminated such unused statements, so that methods contain only code that is being used later on. This would improve the readability and the maintainability of the code. For example in the code below we eliminated the @quiz_phase and the @num_quizzes_total variables because they were not being used anywhere in the code. Also, since the local variables quiz_due_date, deadline_type_id, participant were not being used anywhere, we could eliminate the entire if block from the code below. We then converted the instance variable participant to a local variable because it was not being used in the corresponding view.
 
 
Before Refactoring
 
student_quizzes_controller.rb
 
<pre>
def list
@participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(@participant.user_id)

@assignment = Assignment.find(@participant.parent_id)

# Find the current phase that the assignment is in.
@quiz_phase = @assignment.get_current_stage(AssignmentParticipant.find(params[:id]).topic_id)

@quiz_mappings = QuizResponseMap.where(reviewer_id: @participant.id)

# Calculate the number of quizzes that the user has completed so far.
@num_quizzes_total = @quiz_mappings.size

@num_quizzes_completed = 0
@quiz_mappings.each do |map|
@num_quizzes_completed += 1 if map.response
end

if @assignment.staggered_deadline?
@quiz_mappings.each { |quiz_mapping|
if @assignment.team_assignment?
participant = AssignmentTeam.get_first_member(quiz_mapping.reviewee_id)
else
participant = quiz_mapping.reviewee
end

if !participant.nil? and !participant.topic_id.nil?
quiz_due_date = TopicDeadline.where(topic_id: participant.topic_id, deadline_type_id: 1).first
end
}
deadline_type_id = DeadlineType.find_by_name('quiz').id
end
end
}
</pre>

After Refactoring

<pre>
def index
participant = AssignmentParticipant.find(params[:id])
return unless current_user_id?(participant.user_id)
@assignment = Assignment.find(participant.parent_id)
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
end
</pre>

*Modified declarations of Arrays and Hashes
Before Refactoring :
<pre>

</pre>

After Refactoring :
<pre>

</pre>

*Removed unused methods like self.participants_in and commented out code.

===Following Ruby Style Guidelines (Global Rules)===
At many places in the code we found that the Ruby Style Guidelines were not followed. We have refactored the code so that it uses the good code style guidelines. The following are some of the refactorings the we have done:-
 
==== Used .eql? instead of "==" ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if score.score == -1 </pre>

After Refactoring

<pre> if score.score.eql? -1 </pre>

==== Eliminated the "== true/false" check ====

Before Refactoring
 student_quizzes_controller.rb
 Method : finished_quiz

<pre> if essay_not_graded == true </pre>

After Refactoring

<pre> if essay_not_graded </pre>

==== Use `&&` and `||` rather than `and` and `or` to keep boolean precedence ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre> elsif correct_answer and params["#{question.id}"] == correct_answer.txt </pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre> elsif correct_answer && params["#{question.id}"]== correct_answer.txt </pre>

==== Method names should use underscores, not camelcase. ====

==== Use key: ‘value’, not :key => ‘value’ ====

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>new_score = Score.new comments: choice, question_id: question.id, response_id: response.id</pre>

==== Replace find_by_... with a where command ====
Rails 4 conventions dictate the use of 'where()' over the use of 'find_by_...' methods while querying ActiveRecords. The code has been refactored to replace the usages of find_by.. with where().

 Before Refactoring 
 student_quizzes_controller.rb
 Method: record_response
<pre> if (QuestionType.find_by_question_id question.id).q_type == 'MCC' </pre>

 After Refactoring 
 student_quizzes_controller.rb
 Method: calculate_score
<pre>ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
</pre>

====Use good array checking====

[].empty? # not [].length == 0 or [].length.zero?
[:foo].any? # not [:foo].length > 0
[:foo].one? # not [:foo].length == 1
[:foo].first # not [:foo][0]
[:foo].last # not [:foo][-1]

====Use find_each for efficient loops over models====

SignedUpUser.all.each do |user| # BAD
SignedUpUser.find_each do |user| # GOOD

====Used .nil? instead of "== nil" ====
The inbuilt method .nil? returns a boolean.
 we have used this to replace an == nil check that was there in the code.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
if params["#{question.id}"] == nil
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if params["#{question.id}"].nil?
</pre>

==== Used a Boolean variable when that is sufficient====
It is a good practice to use a boolean variable if we only need a boolean for our purpose.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
valid = 1
if valid == 0
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
valid = false
if valid
</pre>

====Use good conditional statements====
Using unless is a good practice. But it is not a good practice to use unless and ! within the condition.
 Instead we could use an if condition itself.

Before Refactoring
 student_quizzes_controller.rb
 Method: record_response
<pre>
unless new_score.comments != "" && new_score.comments
valid = false
</pre>

After Refactoring
 student_quizzes_controller.rb
 Method: calculate_score
<pre>
if new_score.comments.empty? || new_score.comments.nil?
valid = false
</pre>

====Use of Routing Helpers====
Routing helpers are a simpler alternative to the otherwise complex hard coded URLs which reduce the readability of the code.Routing helpers allow us to declare possible common routes for a given controller. Routing helpers have been implemented since they maintain consistency even if changes are made to the routing paths.

Before Refactoring:
 config.rb does not contain a student_quizzes resource
 review_mapping_controller.rb
<pre>
redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]
</pre>

After Refactoring
 config.rb
<pre>
resources :student_quizzes, :only => [:index]
</pre>
review_mapping_controller.rb
<pre>
redirect_to student_quizzes_path(:id => params[:participant_id])
</pre>

====Replace controller method with a model method ====
Rails 4 conventions dictate the use of a fat model and skinny controller.
It is better to put place the search function in the model rather than placing it in the controller.
The search code belonged to the quiz_response_map model, since it queries that particular table in the DB.
The code was extracted into the subsequent method displayed below and called from the invitation controller.<ref name = "stackoverflow">[http://stackoverflow.com/questions/14044681/fat-models-and-skinny-controllers-sounds-like-creating-god-models StackOverflow]</ref>

Before Refactoring
 student_quiz_controller.rb
<pre>
@quiz_mappings = QuizResponseMap.where(reviewer_id: participant.id)
</pre>

After Refactoring
<pre>
@quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)
</pre>

===Changes made in method logic===
We have made certain changes in the logic of the methods calculate_score and record_response (previously the code of both these methods was only in record_response) primarily to improve the existing logic and eliminate redundant code. These changes are described as follows:

* The score variable was already being set to 0 on the loop entry, therefore it was redundant to reset score to zero again. Thus, we eliminated this line of code inside the if statement.
Before Refactoring
<pre>
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
</pre>

After Refactoring
<pre>
questions.each do |question|
score = 0
if ques_type.eql? 'MCC'
# Eliminated score = 0 over here
</pre>

* The variable correct_answer stored multiple values as the where condition to which it was assigned was returning multiple values. Therefore it seemed more intuitive to rename correct_answer to correct_answers so that it is apparent that it contains multiple values.

Before Refactoring
<pre>
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
</pre>

After Refactoring
<pre>
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
</pre>

* The below piece of code found out the question type twice in the same loop. Therefore we extracted it and assigned it to a local variable so that the query is executed only once.
Before Refactoring
<pre>
# First Query
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
# Repetition of the query in the same loop
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
</pre>

After Refactoring
<pre>
# Querying only once and assigning it to a local variable ques_type
ques_type = (QuestionType.where( question_id: question.id)).q_type
# Usage 1 of ques_type
if ques_type.eql? 'MCC'
# Usage 2 of ques_type
if ques_type.eql? 'Essay'
</pre>

* The new_scores and scores array stored almost the similar values. The scores contained a copy of the value that the new_scores array contained. Therefore we eliminated the new_scores array and are performing all the operations only on the scores array.
Before Refactoring
<pre>
# Part 1
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

# Part 2
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
</pre>
After Refactoring
<pre>
# Part 1
new_score = Score.new comments: choice, question_id: question.id, response_id: response.id

unless new_score.valid?
valid = false
end
scores.push(new_score)

# Part 2
scores.each do |score_update|
score_update.score = score
end
</pre>

* The logic to compute the final score for a multiple-choice, multiple-correct type of question seemed to be incorrect and therefore we fixed it.
Before Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|
correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

# Part 2 of the scoring logic which seems to award full points even if you marked some extra options apart from marking all correct answers
unless score == correct_answer.count
score = 0
else
score = 1
end
</pre>
After Refactoring
<pre>
# Part 1 of the Scoring Logic
questions.each do |question|
score = 0
correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)
ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC'
if params["#{question.id}"].nil?
valid = false
else
params["#{question.id}"].each do |choice|
correct_answers.each do |correct|
if choice.eql? correct.txt
score += 1
end

# Part 2 of the scoring logic - We have also compared the number of options the user selected to the total number of correct answers
if score.eql? correct_answers.count && score == params["#{question.id}"].count
score = 1
else
score = 0
end
</pre>

* The record_response function was performing two distinct operations : One operation was saving the response to the Database and the other was to calculate the score for the questions. We created a new function calculate_score that would calculate the score for the questions and record_response now only performs the task of saving responses to the database.
Before Refactoring
<pre>
def record_response
@map = ResponseMap.find(params[:map_id])
@response = Response.new()
@response.map_id = params[:map_id]
@response.created_at = DateTime.current
@response.updated_at = DateTime.current
@response.save

@questionnaire = Questionnaire.find(@map.reviewed_object_id)
scores = Array.new
new_scores = Array.new
valid = 0
questions = Question.where(questionnaire_id: @questionnaire.id)
questions.each do |question|
score = 0
if (QuestionType.find_by_question_id question.id).q_type == 'MCC'
score = 0
if params["#{question.id}"] == nil
valid = 1
else
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)
params["#{question.id}"].each do |choice|

correct_answer.each do |correct|
if choice == correct.txt
score += 1
end

end
new_score = Score.new :comments => choice, :question_id => question.id, :response_id => @response.id

unless new_score.valid?
valid = 1
end
new_scores.push(new_score)

end
unless score == correct_answer.count
score = 0
else
score = 1
end
new_scores.each do |score_update|
score_update.score = score
scores.push(score_update)
end
end
else
score = 0
correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1).first
if (QuestionType.find_by_question_id question.id).q_type == 'Essay'
score = -1
elsif correct_answer and params["#{question.id}"] == correct_answer.txt
score = 1
end
new_score = Score.new :comments => params["#{question.id}"], :question_id => question.id, :response_id => @response.id, :score => score
unless new_score.comments != "" && new_score.comments
valid = 1
end
scores.push(new_score)
end
end
if valid == 0
scores.each do |score|
score.save
end
redirect_to :controller => 'student_quizzes', :action => 'finished_quiz', :map_id => @map.id
else
flash[:error] = "Please answer every question."
redirect_to :action => :take_quiz, :assignment_id => params[:assignment_id], :questionnaire_id => @questionnaire.id
end

end
</pre>

After Refactoring
<pre>
# New record_response method
def record_response
map = ResponseMap.find(params[:map_id])
response = Response.new
response.map_id = params[:map_id]
response.created_at = DateTime.current
response.updated_at = DateTime.current
response.save

calculate_score map,response

end

# New calculate_score
def calculate_score map, response
# The entire logic below the response.save line from the earlier record_response method goes here.
</pre>

==References==
<references/>