CSC/ECE 517 Fall 2014/OSS E1466 gjf

E1466: Refactoring GradesController

This wiki deals with our implementation of a controller in expertiza: grade_controller for the Expertiza Project using Ruby on Rails.

Introduction

Expertiza is a web application where students can submit and peer-review learning objects (articles, code, web sites, etc). It is used in select courses at NC State and by professors at several other colleges and universities.

Project Description

Classes involved: grades_controller.rb

What it does:

This class lists the grades of all the participants for an assignments and also their reviews. Instructor can edit scores, calculate penalties and send emails for conflicts.

What needs to be done:

• Modify calculate_all_penalties method which is too complex and long.
• Put the get_body_text method in a mailer rather than in the grades_controller.
• Refactor conflict_nofication method to conflict_email and make it delegated to the mailer.
• Refactor view_my_scores method to grades_show and delete the unnecessary variables.
• Refactored get_assessments_for method in response_map.rb and lead to more than 90% off the current waiting time.
• Try not to query for reviews and meta reviews in grades_show method.

Code Modification

calculate_all_penalties Method

Summary

We have modified the calculate_penalties method and implemented all the functions it originally has. After our modification the method shrinks from 45 lines to 32 lines of Ruby code. Originally, the method includes a lot of unnecessary if and unless statements which makes the method uneasy to read and seems to have a difficult logic to calculate the penalties.

According to the codeclimate which calculate the complexity of the method, originally, it has a complexity of 85, however, after we modified it, the complexity goes down to 65. Please check at original version,modified version

We have done the following to the original methods:

• Used for loop with selective choice to create penalty attributes and put it into the CalculatedPenalty Table, instead of duplicating the almost same code.

• Used Object-Oriented Design patterns of Ruby: let the array respond to the method min which returns the minimum number in the array and get the logical penalty other than using if statement.(max_penalty if total_penalty is larger than max_penalty, total_penalty if total_penalty is smaller than max_penalty)

• Eliminated the unnecessary if statements to make the code clear to read.

Implementation

• Modify if statements:

Before Refactoring:

 if(penalties[:submission].nil?)
      penalties[:submission]=0
 end
 if(penalties[:review].nil?)
      penalties[:review]=0
 end
 if(penalties[:meta_review].nil?)
      penalties[:meta_review]=0
 end

After Refactoring:

penalties[:submission] = 0 if penalties[:submission].nil?
penalties[:review] = 0 if penalties[:review].nil?
penalties[:meta_review] = 0 if penalties[:meta_review].nil?

• Using Objected-oriented Pattern

Before Refactoring:

 if(@total_penalty > l_policy.max_penalty)
      @total_penalty = l_policy.max_penalty
 end

After Refactoring:

 @total_penality=[l_policy.max_penalty,@total_penality].min

• Using loops rather than duplicate same code

Before Refactoring:

 penalty_attr1 = {:deadline_type_id => 1,:participant_id => @participant.id, :penalty_points => penalties[:submission]}
       CalculatedPenalty.create(penalty_attr1)
 penalty_attr2 = {:deadline_type_id => 2,:participant_id => @participant.id, :penalty_points => penalties[:review]}
       CalculatedPenalty.create(penalty_attr2)
 penalty_attr3 = {:deadline_type_id => 5,:participant_id => @participant.id, :penalty_points => penalties[:meta_review]}
       CalculatedPenalty.create(penalty_attr3)"
 @all_penalties[participant.id] = Hash.new
       @all_penalties[participant.id][:submission] = penalties[:submission]
       @all_penalties[participant.id][:review] = penalties[:review]
       @all_penalties[participant.id][:meta_review] = penalties[:meta_review]
       @all_penalties[participant.id][:total_penalty] = @total_penalty"

After Refactoring:

 deadline_type=[1,2,5]
 penalty_type=[:submission,:review,:meta_review]
 if calculate_for_participants
      for i in 0..2
           penalty_attr={:deadline_type_id=>deadline_type[i],:participant_id => @participant.id, :penalty_points => penalties[penalty_type[i]]}
           CalculatedPenalty.create(penalty_attr)
      end
 end
 @all_penalties[participant.id] = {}
      for i in 0..2
          @all_penalties[participant.id][:penalty_type[i]] = penalties[:penalty_type[i]]
      end
 @all_penalties[participant.id][:total_penalty] = @total_penalty"

conflict_notification Method

Summary

We refactored the conflict_notification method to conflict_email method. When instructor click the button "email reviewer" whom he thought give a unfair review, the system should be able to send an email to the reviewer automatically.

Implementation

The old conflict_notification action queries an email address list of a certain kind of reviews. In its view conflict_notification.html.erb, A email form contains email list for instructor to choose from and email content.

Before Refactoring, in conflict_notification: First,Get the instructor email address as sender

 
      if session[:user].role_id !=6             
        @instructor = session[:user]
      else
        @instructor = Ta.get_my_instructor(session[:user].id)
      end
      @participant = AssignmentParticipant.find(params[:id])
      @assignment = Assignment.find(@participant.parent_id)

Then,Based on submission of review, the action query all the reviewers' email address

  
      @questions = Hash.new
      questionnaires = @assignment.questionnaires
      questionnaires.each {
        |questionnaire|
        @questions[questionnaire.symbol] = questionnaire.questions
      }

The email list is for instructor to choose from. The process_response method queries the email address.

  
      @reviewers_email_hash = Hash.new            
      @caction = "view"
      @submission = params[:submission]
      if @submission == "review"
        @caction = "view_review"
        @symbol = "review"
        process_response("Review", "Reviewer", @participant.reviews, "ReviewQuestionnaire")
      elsif @submission == "review_of_review"
        @symbol = "metareview"
        process_response("Metareview", "Metareviewer", @participant.metareviews, "MetareviewQuestionnaire")
      elsif @submission == "review_feedback"
        @symbol = "feedback"
        process_response("Feedback", "Author", @participant.feedback, "AuthorFeedbackQuestionnaire")
      elsif @submission == "teammate_review"
        @symbol = "teammate"
        process_response("Teammate Review", "Reviewer", @participant.teammate_reviews, "TeammateReviewQuestionnaire")
      end

The get_body_text method construct email content also in controller

                                               
      @body = get_body_text(params[:submission])      

The conflict_notification action requiring another two method "process_response" and "get_body_text" method to get the recipient email list and email content which contributes to extra complexity. The instructor only have to click the button "send email" in conflict_notification.html.erb and turn to send_conflict_email action, then he/she can send the email. If the instructor want to send another email, the process will repeat again,which will be terrible when reloading the "view" scores page.

After Refactoring:The quering reiviews actually have done in our show_reviews action, and we can get the individual reviewers' email address.In the reviewer table,we add extra button "email reviewer".Now the instructor could send to reviewer email directly.

In _review_table.html.erb,we add the link to send email. The review_id is passed to the conflict_email action taken as the recipient.

<%= link_to 'email reviewer', :action => 'conflict_email',:remote=> true,:reviewer_id=> 

review.map.reviewer.user,:participant_id=>participant,:score=>sprintf("%.2f",score) %>

In our new conflict_email action:

We still need the instructor as the sender

      if session[:user].role_id !=6
        @instructor = session[:user]
      else
        @instructor = Ta.get_my_instructor(session[:user].id)
      end

The reviewer_id is passed from the link,we can query his/her email address to send the email

      recipient=User.find(params[:reviewer_id])

The responsibility of sending email has been delegated to a new mailer conflict_mailer. And the email content was constructed in the mailer.

      participant = AssignmentParticipant.find(params[:participant_id])
      assignment=Assignment.find(participant.parent_id)      
      score=params[:score]
      ConflictMailer.send_conflict_email(instructor,recipient,assignment,score).deliver

Take a look at new conflict_mailer, it define a send_conflict_email method. the email was sent from sender's email and to reviewer's email.Some instance variables were used in view. In conflict_mailer.erb

 def send_conflict_email(sender,recipient,assignment,score)
      @assignment=assignment
      @recipient=recipient
      @score=score
      if recipient.role_id==1
        @role = "reviewer"
        @item = "submission"
      else
        @role = "metareviewer"
        @item = "review"
      end
    mail subject: "Conflication Email",from: sender.email,to: reviewer.email
  end

In its view send_conflict_email.txt.haml, we construct the email content.By this way, we follow the rule of MVC design

%h1="Hi ," +@recipient.name

%p="You submitted a score of "+@score+" for assignment "+@assignment.name+" that varied greatly from another "+@role+"'s score for the same "+@item+"."

%p="The Expertiza system has brought this to my attention."

The link "email reviewer" request a ajax,so the current view page will not refresh when the action done

      respond_to do |format|
        format.js
      end

If an email was successfully sent,The instructor should get the alert window by ajax.

view_my_scores method

Summary

We refactored view_my_scores method to grades_show, deleted many unnecessary instance variables along with several review and meta reviews methods inside it. Therefore, the system will only search for scores in the database rather than search for scores and reviews, which wastes a lot of time during the grade show process. After refactoring, the complexity on this decreased from 53 to 35. We also optimize get_scores method to improve the efficiency of showing scores by students and instructors, which cost us most of the time during the project. After refactoring this method, the time cost of views in grade controller decreased by more than 90%.

We have done the following to the original methods:

• Refactored view_my_scores method to grades_show method.

• Searched for the key reasons which lead to huge waiting time for getting score.

• Refactored get_assessments_for method in response_map.rb and lead to more than 90% off the current waiting time.

• Eliminated the search for reviews during the grades_show method.

• Deleted unnecessary instance Variables.

Implementation

• Deleted the unnecessary instance variables

Deleted Code:

 @average_score_results = Array.new
 @average_score_results = ScoreCache.get_class_scores(@participant.id)
 @statistics = Array.new
 @average_score_results.each { |x|
 @statistics << x
 }

• Deleted query for reviews and meta_reviews

Deleted Code:

 @average_reviews = ScoreCache.get_reviews_average(@participant.id)
 @average_metareviews = ScoreCache.get_metareviews_average(@participant.id)
 @my_reviews = ScoreCache.my_reviews(@participant.id)
 @my_metareviews = ScoreCache.my_metareviews(@participant.id)

• Modify get_assessments_for method in response_map.rb

After doing this, the time cost of view function decreased by more than 90% Before Refactoring:

 # the original method to find all response 
 @all_resp=Response.all
 for element in @all_resp
     if (element.map_id == map.map_id)
         @array_sort << element
         @test << map
     end
 end

After Refactoring:

 @all_resp=Response.find_by_map_id(map.map_id)
 @array_sort << @all_resp
 @test << map

• Add a new method into grades_controller.rb

Add Method:

 #show_reviews method gets reviews, meta reviews and author feedback information from server.
  def show_reviews
    @partial='grades/'+params[:path]
    @prefix=params[:prefix]
    @score=Hash.new
    @score[:assessments]=Array.new
    params[:score][:assessments].each do |assessment|
        @score[:assessments]<<Response.find(assessment)
    end
    @score[:scores]=params[:score][:scores]
    @participant=AssignmentParticipant.find(params[:participant])
    @assignment = @participant.assignment
    @questions = {}
    questionnaires = @assignment.questionnaires
    questionnaires.each do |questionnaire|
      @questions[questionnaire.symbol] = questionnaire.questions
    end
  end

• Change view_my_score.html.erb into show_reviews.html.erb in views.

• Add in views(show_reviews.html.erb)

 <%= render :partial=>@partial, :locals => {:prefix => @prefix, :participant => @participant, :rscore => @score} %>

Test Result

• The following test results based on the test case on Expertiza(Assignments: Program 2 style)

Name	Before Refactoring	After Refactoring	Reduced By
View all team's score(instructor)	484988ms	8642ms	98.21%
View own score(student)	8941ms	651ms	92.71%

• Original Time for Instructor to View all scores

Original Time for Instructor to View all scores

• Time for Instructor to View all scores after Refactoring

Time for Instructor to View all scores after Refactoring

• Original Time for Student to View all scores

Original Time for Student to View all scores

• Time for Student to View all scores after Refactoring

Time for Student to View all scores after Refactoring