CSC/ECE 517 Spring 2018- Project E1808: Refactor review mapping controller.rb

Introduction

Expertiza Overview

Expertiza is a platform through which students are able to view and manage their assignments, form teams for a group project and review other team's work for improvement. It uses Ruby on Rails Framework

Objectives of the Project

• Refactor automatic_review_mapping method
  • Write failing tests first
  • Split into several simpler methods and assign reasonable names
  • Extract duplicated code into separate methods
• Refactor response_report method
  • Write failing tests first
  • Use factory pattern to create a corresponding report according to the switch condition
  • Create corresponding helper classes for different report types

Implementation

Files editted

• review_mapping_controller.rb
• automatic_review_mapping_helper.rb

About Review Mapping Controller

Review mapping controller handles the review responses that are done on every assignment. It assigns reviews to different teams or individual student depending on the type of assignment(team project or individual project). It keeps track that all the teams are reviewed and assigned teams to review too.

Refactoring

Refactoring is used to improve a design code by changing the structure of the code such that the functionality remains the same. The changes made are quite small, but the overall effect becomes significant.

Refactoring automatic_review_mapping method

As this method was long and complex it needed to be broken down into smaller methods with specific functionality.

Original:

def automatic_review_mapping
    assignment_id = params[:id].to_i
    participants = AssignmentParticipant.where(parent_id: params[:id].to_i).to_a.reject {|p| p.can_review == false }.shuffle!
    teams = AssignmentTeam.where(parent_id: params[:id].to_i).to_a.shuffle!
    max_team_size = Integer(params[:max_team_size]) # Assignment.find(assignment_id).max_team_size
    # Create teams if its an individual assignment.
    if teams.empty? and max_team_size == 1
      participants.each do |participant|
        user = participant.user
        next if TeamsUser.team_id(assignment_id, user.id)
        team = AssignmentTeam.create_team_and_node(assignment_id)
        ApplicationController.helpers.create_team_users(participant.user, team.id)
        teams << team
      end
    end
    student_review_num = params[:num_reviews_per_student].to_i
    submission_review_num = params[:num_reviews_per_submission].to_i
    calibrated_artifacts_num = params[:num_calibrated_artifacts].to_i
    uncalibrated_artifacts_num = params[:num_uncalibrated_artifacts].to_i

    if calibrated_artifacts_num == 0 and uncalibrated_artifacts_num == 0
      if student_review_num == 0 and submission_review_num == 0
        flash[:error] = "Please choose either the number of reviews per student or the number of reviewers per team (student)."
      elsif (student_review_num != 0 and submission_review_num == 0) or (student_review_num == 0 and submission_review_num != 0)
        # REVIEW: mapping strategy
        automatic_review_mapping_strategy(assignment_id, participants, teams, student_review_num, submission_review_num)
      else
        flash[:error] = "Please choose either the number of reviews per student or the number of reviewers per team (student), not both."
      end
    else
      teams_with_calibrated_artifacts = []
      teams_with_uncalibrated_artifacts = []
      ReviewResponseMap.where(reviewed_object_id: assignment_id, calibrate_to: 1).each do |response_map|
        teams_with_calibrated_artifacts << AssignmentTeam.find(response_map.reviewee_id)
      end
      teams_with_uncalibrated_artifacts = teams - teams_with_calibrated_artifacts
      # REVIEW: mapping strategy
      automatic_review_mapping_strategy(assignment_id, participants, teams_with_calibrated_artifacts.shuffle!, calibrated_artifacts_num, 0)
      # REVIEW: mapping strategy
      # since after first mapping, participants (delete_at) will be nil
      participants = AssignmentParticipant.where(parent_id: params[:id].to_i).to_a.reject {|p| p.can_review == false }.shuffle!
      automatic_review_mapping_strategy(assignment_id, participants, teams_with_uncalibrated_artifacts.shuffle!, uncalibrated_artifacts_num, 0)
    end
    redirect_to action: 'list_mappings', id: assignment_id
  end

After Refactoring:

def automatic_review_mapping
    count = 0 # this variable is used to control whether the calibrated or the uncalibrated automatic_review_map_controller_strategy will be called on yield.
    helper = AutomaticReviewMappingHelper::AutomaticReviewMappingHelper.new(params)
    # Create teams if its an individual assignment.
    helper.create_teams_if_individual_assignment
    if helper.check_if_all_artifacts_num_are_zero(params)
       helper.assign_reviews_for_artifacts_num_zero(params) do |error|
        if error
          flash[:error] = error.message
        else
        automatic_review_mapping_strategy(helper.assignment_id, helper.participants, helper.teams, helper.student_review_num, helper.submission_review_num)
        end
        end
    else
       helper.assign_reviews_for_artifacts_num_not_zero(params) do
        automatic_review_mapping_strategy(helper.assignment_id, helper.participants, helper.teams_with_calibrated_artifacts.shuffle!, helper.calibrated_artifacts_num, 0) if count == 0
        count = count+1
        if count == 2 
          automatic_review_mapping_strategy(helper.assignment_id, helper.participants, helper.teams_with_uncalibrated_artifacts.shuffle!, helper.uncalibrated_artifacts_num, 0)
          count == 0
        end
      end
    end

    redirect_to action: 'list_mappings', id: helper.assignment_id
  end

Approach

As seen, the method originally was very long and complex. So, the method was broken down into smaller methods. These smaller methods perform various tasks in the review mapping controller. As tey show similar behavior they were grouped in a helper class: AutomaticReviewMappingHelper.

Methods

1. initialize
2. create_teams_if_individual_assignment
3. check_if_all_artifacts_num_are_zero
4. assign_reviews_for_artifacts_num_zero
5. assign_reviews_for_artifacts_num_not_zero

The common parameters that are used in the automatic review mapping method are defined here so that they can be used as instance variables throughout for better flow of the code.

	def initialize(params)
		@assignment_id = params[:id].to_i
    		@participants = AssignmentParticipant.where(parent_id: params[:id].to_i).to_a.reject {|p| p.can_review == false }.shuffle!
    		@teams = AssignmentTeam.where(parent_id: params[:id].to_i).to_a.shuffle!
    		@max_team_size = Integer(params[:max_team_size]) # Assignment.find(assignment_id).max_team_size
    		@student_review_num = params[:num_reviews_per_student].to_i
    		@submission_review_num = params[:num_reviews_per_submission].to_i
    		@calibrated_artifacts_num = params[:num_calibrated_artifacts].to_i
    		@uncalibrated_artifacts_num = params[:num_uncalibrated_artifacts].to_i
    		@teams_with_calibrated_artifacts = []
      		@teams_with_uncalibrated_artifacts = []
    	end

 
   	def create_teams_if_individual_assignment
    		if @teams.empty? and @max_team_size == 1
     			 @participants.each do |participant|
        		 next if TeamsUser.team_id(@assignment_id, participant.user.id)
        		 team = AssignmentTeam.create_team_and_node(@assignment_id)
        		 ApplicationController.helpers.create_team_users(participant.user, team.id)
        		 @teams << team
                 end
    		end
    	end

This method checks for the value of num_calibrated_artifacts and uncalibrated_artifacts. If both are zero, it returns true to the controller and the controller then calls the assign_reviews_for_artifacts_num_zero method. If both the values are not zero, 'false' is returned to the controller and controller calls assign_reviews_for_artifacts_num_not_zero method

    	def check_if_all_artifacts_num_are_zero(params)
    		
    		if @calibrated_artifacts_num == 0 and @uncalibrated_artifacts_num == 0
    			true
    		else
    			false
    		end

    	end

Use of 'Yield'

The keyword yield is used in the two helper class methods( assign_reviews_for_artifacts_num_zero and assign_reviews_for_artifacts_num_not_zero) as the functionality of these two methods require to call a controller method(automatic_review_mapping_strategy) inside them. As it is not a good practice to call controller methods in helper class, we transfer the control from the helper class method back to the controller so that we don't have to create controller object in the helper class. The variable count in the controller is used to differentiate the call of automatic_review_mapping_strategy method. The value of the count decides which method call is associated with the yield in the helper method.

Exceptions in Helper Methods

As it not a good practice to have flash errors in helper methods(as flash needs to be passed as a parameter) exceptions are raised in helper class methods. So when these exceptions are raised in the helper class, they are picked up by the controller and controller displays the corresponding error message associated with it. This reduces the complexity of the code.

    	def assign_reviews_for_artifacts_num_zero(params)
    		
    			if @student_review_num == 0 and @submission_review_num == 0
    				begin
        			raise "Please choose either the number of reviews per student or the number of reviewers per team (student)."
        			rescue Exception => e
        			yield e
        		    end
        			#flash[:error] = "Please choose either the number of reviews per student or the number of reviewers per team (student)."
      			elsif (@student_review_num != 0 and @submission_review_num == 0) or (@tudent_review_num == 0 and @submission_review_num != 0)
        			# REVIEW: mapping strategy
             		yield
      			else
      				begin
        			raise "Please choose either the number of reviews per student or the number of reviewers per team (student), not both."
        			rescue Exception => e
        			yield e
        			#flash[:error] = "Please choose either the number of reviews per student or the number of reviewers per team (student), not both."
            		end
           
            	end
    	end

    	def assign_reviews_for_artifacts_num_not_zero(params)
    		
    		ReviewResponseMap.where(reviewed_object_id: @assignment_id, calibrate_to: 1).each do |response_map|
        	@teams_with_calibrated_artifacts << AssignmentTeam.find(response_map.reviewee_id)
      		end
      		@teams_with_uncalibrated_artifacts = @teams - @teams_with_calibrated_artifacts
      		# REVIEW: mapping strategy
      		yield
      		
      		# REVIEW: mapping strategy
      		# since after first mapping, participants (delete_at) will be nil
      		@participants = AssignmentParticipant.where(parent_id: params[:id].to_i).to_a.reject {|p| p.can_review == false }.shuffle!
      		yield
      		

    	end

Controller Method:

 if helper.check_if_all_artifacts_num_are_zero(params)
       helper.assign_reviews_for_artifacts_num_zero(params) do |error|
        if error
          flash[:error] = error.message
        else
        automatic_review_mapping_strategy(helper.assignment_id, helper.participants, helper.teams, helper.student_review_num, helper.submission_review_num)
        end
        end
    else
       helper.assign_reviews_for_artifacts_num_not_zero(params) do
        automatic_review_mapping_strategy(helper.assignment_id, helper.participants, helper.teams_with_calibrated_artifacts.shuffle!, helper.calibrated_artifacts_num, 0) if count == 0
        count = count+1
        if count == 2 
          automatic_review_mapping_strategy(helper.assignment_id, helper.participants, helper.teams_with_uncalibrated_artifacts.shuffle!, helper.uncalibrated_artifacts_num, 0)
          count == 0
        end
      end

Results

Tests for the two methods were already present in review_mapping_controller_spec.rb So after the refactoring was done all the tests pass reflecting that the functionality of the code remains same after refactoring.