CSC/ECE 517 Spring 2015/oss E1505 xzl

Expertiza - Refactoring AssignmentParticipant model

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>Expertiza on GitHub</ref><ref>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.

Project Description

The AssignmentParticipant model is subclass of Participant model and is used to maintain the list of students/users participating in a given assignment.
The changes that are needed to be done are described as follows:<ref>GoogleDoc for our project requirements</ref>

1. Rename methods prefixed with “get”.
2. Move methods to appropriate file helper classes.
3. Move methods to appropriate models.
4. Remove unused methods
5. Use good Ruby style guidelines in the code.

Modifications made to the Existing Code

Rename methods prefixed with “get”

---

According to Ruby naming conventions, the name of getter and setter methods need not to be verbs and they should not be prefixed with "get".
The following methods were renamed.

get_reviewers => reviewers
get_scores => scores
get_members => members
get_team_hyperlinks => team_hyper_links
get_hyperlinks_array => hyperlinks_array
get_course_string => course_string
get_feedback => feedback
get_reviews => reviews
self.get_export_fields => self.export_fields
get_path => path
get_current_stage => current_stage
def get_stage_deadline => def stage_deadline

Move methods to appropriate file helper classes

---

Methods get_submitted_files, get_files should not be in this class. They deal with files and should be moved to appropriate file helper classes.

Move methods to appropriate models

---

reviewed_by? , quiz_taken_by? do not belong to AssignmentParticipant model. Move them to appropriate models. Because in the reviewed_by? method the keyword ParticipantReviewResponseMap is referenced, so we move the method reviewed_by? to model app/models/participant_review_response_map.rb, also the same to quiz_taken_by?, since the keyword QuizQuestionnaire is referenced in method quiz_taken_by?, so we move it to model app/models/quiz_questionnaire.rb. Also We did the same operation to method get_quizzes_taken to move it to app/models/quiz_response_map.rb.
Below we use a pair picture of method reviewed_by? as an example to demonstrate operation of this category.

Remove unused methods

---

Methods is_reviewed_by? , quiz_taken_by? are not getting invoked from anywhere. Find all such methods to see if we need them and delete the methods if we don’t need them. Additionally, get_two_node_cycles, get_three_node_cycles, get_four_node_cycles, get_cycle_similarity_score, get_cycle_deviation_score are also available in CollusionCycle model. Determine if we need them in AssignmentParticipant model and delete the methods if we don’t need them.
The following method are removed:

average_score_per_assignment(assignment_id)
quiz_taken_by?(contributor, reviewer)
has_quiz?
reviewees
get_two_node_cycles
get_three_node_cycles
get_four_node_cycles
get_cycle_similarity_score(cycle)
get_cycle_deviation_score(cycle)
get_reviews_by_reviewer(reviewer)

Use good Ruby style guidelines in the code

---

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

 if score.score == -1 

After Refactoring

 if score.score.eql? -1 

Eliminated the "== true/false" check

---

Before Refactoring
Method : finished_quiz

 if essay_not_graded == true 

After Refactoring

 if essay_not_graded 

Use `&&` and `||` rather than `and` and `or` to keep boolean precedence

---

Before Refactoring
Method: record_response

 elsif  correct_answer and params["#{question.id}"] == correct_answer.txt 

After Refactoring
Method: calculate_score

 elsif  correct_answer && params["#{question.id}"]== correct_answer.txt 

Use key: ‘value’, not :key => ‘value’

---

Before Refactoring
Method: record_response

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

After Refactoring
Method: calculate_score

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

Replace find_by_... with a where command

---

Before Refactoring
Method: record_response

 if (QuestionType.find_by_question_id question.id).q_type == 'MCC' 

After Refactoring
Method: calculate_score

ques_type = (QuestionType.where( question_id: question.id)).q_type
if ques_type.eql? 'MCC' 

Used .nil? instead of "== nil"

---

Before Refactoring
Method: record_response

if params["#{question.id}"] == nil

After Refactoring
Method: calculate_score

if params["#{question.id}"].nil?

Used a Boolean variable when that is sufficient

---

Before Refactoring
Method: record_response

valid = 1
 if valid == 0

After Refactoring
Method: calculate_score

valid = false
 if valid

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

unless new_score.comments != "" && new_score.comments
   valid = false

After Refactoring
Method: calculate_score

if new_score.comments.empty? || new_score.comments.nil?
   valid = false

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

redirect_to :controller => 'student_quizzes', :action => 'index', :id => params[:participant_id]

After Refactoring
config.rb

resources :student_quizzes, :only => [:index]

review_mapping_controller.rb

redirect_to student_quizzes_path(:id => params[:participant_id])

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">Fat Models and Skinny Controllers.</ref>

Before Refactoring
student_quizzes_controller.rb
Method : index

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

After Refactoring
student_quizzes_controller.rb
Method : index

 @quiz_mappings = QuizResponseMap.get_mappings_for_reviewer(participant.id)

quiz_response_map.rb

def self.get_mappings_for_reviewer(participant_id)
  return QuizResponseMap.where(reviewer_id: participant_id)
end

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

questions.each do |question|		
  score = 0		
  if (QuestionType.find_by_question_id question.id).q_type == 'MCC'		
    score = 0

After Refactoring

questions.each do |question|
 score = 0
 if ques_type.eql? 'MCC'
    # Eliminated score = 0 over here

---

• 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

correct_answer = QuizQuestionChoice.where(question_id: question.id, iscorrect: 1)

After Refactoring

correct_answers = QuizQuestionChoice.where(question_id: question.id, iscorrect: true)

---

• 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

# 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'

After Refactoring

# 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'

---

• 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

# 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

After Refactoring

# 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

---

• 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

# 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

After Refactoring

# 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

---

• 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>O-O Design Principles</ref>

Before Refactoring

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

After Refactoring

# 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

References

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