CSC/ECE 517 Spring 2016/Refactor review mapping controller.rb

E1615. Refactoring the Review Mapping Controller

This page provides details about the OSS project which was based on refactoring one of controllers related to peer reviewing strategies used in Expertiza.

About Review mapping controller

Review mapping controller contains methods related to peer reviewing strategies. It contains methods to add a reviewer, delete a reviewer, selecting a reviewer. Depending on the number of students and number of submissions, the topics to be reviewed are assigned to the students automatically. If a user wants to look for the team for a submission , it returns the team by comparing the submission id's with the team id's. Also, it assigns quizzes dynamically. Generation of review report, feedback report and teammate review is done.

Code Improvements

1. Unused variables and arguments

There are unused variables in the methods which use the stack unnecessarily. So, it is better to remove the unused variables or at the least indicate that a variable is unused.

For suppose when both keys and values are not used in a hash but are given as arguments, then the unused variables can be indicated by adding a "_" infront of the name or replaced with "_" to represent it as unused variable but allow them arguments.

Previous Code: teams_hash = unsorted_teams_hash.sort_by{|k, v| v}.to_h

After Changing the code: teams_hash = unsorted_teams_hash.sort_by{|_, v| v}.to_h

In the above case teams_hash should consist of a hash with both keys and values but the sorting is done based on values. So the key is replaced with a "_" so that the user may deem it unused in the implementation of the process.

2. Use sample instead of shuffle

When sample is used, the elements in an array are chosen by using random and unique indices in the array so that the elements doesn't repeat in the array. This cannot be guaranteed in shuffle. Also by using shuffle[0] we are shuffling all the elements in the array and then picking the first element instead of picking a single element randomly which is more efficient. The following are the couple of places where shuffle[0] was used and is replaced by sample.

Previous Code:

assignment_team = assignment_teams.to_a.shuffle[0] rescue nil

topic = assignment.candidate_topics_to_review(reviewer).to_a.shuffle[0] rescue nil

After Changing the code:

assignment_team = assignment_teams.to_a.sample rescue nil

topic = assignment.candidate_topics_to_review(reviewer).to_a.sample rescue nil

3. Cyclomatic complexity of automatic_review_mapping_strategy method

The method automatic_review_mapping_strategy handles the number of reviews assigned to a individual and also the number of reviews that can be done with in a team. The method is very long and has many nested if statements due to which the complexity of the method is very high. Instead of a single method handling all the parts of the strategy, it is divided into several parts due to which the code is more readable and also the complexity of code is shared by each method.

The method first checks the number of participants that are in an assignment and the number of teams that are present. It then sets the values for the maximum number of reviews that are possible and also the minimum number that are required. Then it assigns the reviews to each of the teams randomly when a request for review is made by a participant. At last it checks if the participant has the minimum number of reviews required after allotting the reviews. If not, it assigns more reviews to valid teams so that the minimum requirement is met.

The part of the method which assigns reviews to teams automatically is divided into a separate method called peer_review_strategy.

4. Moving code specific to models to models instead of controller

The method response_report contains code which generates reports based on the input of one of the three of 'ReviewResponseMap', 'FeedbackResponseMap', 'TeammateReviewResponseMap' and 'Calibration'. Calibration is a special case and should be handled in the controller itself. But the other three are models that are subclasses of ResponseMap model. The report is generated for each of the three by calling the ResponseMap model and obtaining the values by querying the database. Moving the code to the models and calling the methods in the model through the controller makes more sense than writing the code in controller.

The following is the code snippet from the original method which contains the calls to ResponseMap model:

case @type
    when "ReviewResponseMap"
      if params[:user].nil?
        # This is not a search, so find all reviewers for this assignment
        response_maps_with_distinct_participant_id = ResponseMap.select("DISTINCT reviewer_id").where(["reviewed_object_id = ? and type = ? and calibrate_to = ?", @id, @type, 0])
        @reviewers = []
        response_maps_with_distinct_participant_id.each do |reviewer_id_from_response_map|
          @reviewers << (AssignmentParticipant.find(reviewer_id_from_response_map.reviewer_id))
        end
        @reviewers = Participant.sort_by_name(@reviewers)
      else
        # This is a search, so find reviewers by user's full name
        user = User.select("DISTINCT id").where(["fullname LIKE ?", '%'+params[:user][:fullname]+'%'])
        @reviewers = AssignmentParticipant.where(["user_id IN (?) and parent_id = ?", user, @assignment.id])
      end
      #  @review_scores[reveiwer_id][reviewee_id] = score for assignments not using vary_rubric_by_rounds feature
      # @review_scores[reviewer_id][round][reviewee_id] = score for assignments using vary_rubric_by_rounds feature
      @review_scores = @assignment.compute_reviews_hash
      @avg_and_ranges= @assignment.compute_avg_and_ranges_hash
    when "FeedbackResponseMap"
      #Example query
      #SELECT distinct reviewer_id FROM response_maps where type = 'FeedbackResponseMap' and 
      #reviewed_object_id in (select id from responses where 
      #map_id in (select id from response_maps where reviewed_object_id = 722 and type = 'ReviewResponseMap'))
      @review_response_map_ids = ResponseMap.select("id").where(["reviewed_object_id = ? and type = ?", @id, 'ReviewResponseMap'])
      @response_ids = Response.select("id").where(["map_id IN (?)", @review_response_map_ids])
      @reviewers = ResponseMap.select("DISTINCT reviewer_id").where(["reviewed_object_id IN (?) and type = ?", @response_ids, @type])
    when "TeammateReviewResponseMap"
      #Example query
      #SELECT distinct reviewer_id FROM response_maps where type = 'TeammateReviewResponseMap' and reviewed_object_id = 711
      @reviewers = ResponseMap.select("DISTINCT reviewer_id").where(["reviewed_object_id = ? and type = ?", @id, 'TeammateReviewResponseMap'])
    end
  end

The same code after moving the methods to their respective models looks as follows:

case @type
      when "ReviewResponseMap"
        @review_user= params[:user]
        #If review response is required call review_response_report method in review_response_map model
        @reviewers = ReviewResponseMap.review_response_report(@id, @assignment,@type, @review_user)
        @review_scores = @assignment.compute_reviews_hash
        @avg_and_ranges= @assignment.compute_avg_and_ranges_hash
      when "FeedbackResponseMap"
        #If review report for feedback is required call feedback_response_report method in feedback_review_response_map model
        @reviewers = FeedbackResponseMap.feedback_response_report(@id, @type)
      when "TeammateReviewResponseMap"
        #If review report for teammate is required call teammate_response_report method in teammate_review_response_map model
        @reviewers = TeammateReviewResponseMap.teammate_response_report(@id)
    end
  end

References

1. Expertiza on GitHub
2. Forked repository for the project
3. Expertiza Main Page