CSC/ECE 517 Spring 2015/oss E1501 YWS

E1501: Refactoring Assignments.rb

This page provides information about a project which aims to refactor Assignment.rb file present in Expertiza OSS.

Introduction to Expertiza

Expertiza is an open source project developed using the Ruby on Rails platform. It provides features like team assignments, peer review, submission of projects, grading etc. The code can be cloned from GitHub. This application provides an efficient way to manage assignments, grades and reviews, which makes the process easier and faster when the class strength is large.

Assignment.rb is a file which contains the assignment model and the related functionality. It also contains the score module which is refactored to make the file more clean and easy to read.

Problem Statement

Classes involved:

assignment.rb
scorable.rb
Gemfile
schema.rb

What they do

Assignment.rb along with the controller file is responsible for creating and editing the assignments. The file also contains the functions responsible for grading.

What needs to be done:

The assignment model needed a refactoring as it contains some modules which were responsible for generating assignment scores. Moreover, the querying module was database dependent which was made database independent. There were many function names and code lines which were not following the ruby guidelines. They were changed to more ruby like coding style.

Re-factored Instances

Instance 1 : Refactoring the Assignment.rb

Creation of separate model scorable.rb

There are many methods which are not directly related to assignments. These methods are responsible for generating the scores and related functions. These methods are:

1.get_scores

2.get_max_score_possible

3.compute_reviews_hash

4.get_average_score

All these methods are taken out of assignment.rb and pushed into a new file "scorable.rb". This made score generation a separate module and the dependency of scores on assignments have been reduced significantly.

Make assignment.rb more Ruby like

There were many instances where the coding style was not according to ruby guidelines. The code was refactored to be more ruby like. Changes such as removing the return type, writing .each instead of for loop and improved naming conventions were implemented. Some of the changes are described below:

Before Change

 quiz_response_mappings.each do |qmapping|
   if qmapping.response
     quiz_responses << qmapping.response
   end
 end

After Change

 quiz_responses = quiz_response_mappings.select{ |qmapping| qmapping.response }.map(&:response)

Before Change

 total = 0
 self.questionnaires.each { |questionnaire| total += questionnaire.get_weighted_score(self, scores) }
 total

After Change

 self.questionnaires.inject(0) { |total, questionnaire| total + questionnaire.get_weighted_score(self, scores) }

Instance 2 : Addition of ActiveRecord like Query

The queries where changed to function more like active record query. This made the queries database independent and more user friendly.

Before Change

  DueDate.where( ['assignment_id = ? and deadline_type_id >= ?', self.id, 7]).due_at

After Change

  DueDate.where(assignment_id: self.id, deadline_type_id: 7).due_at

Refactoring view code into relevant views

There were no edit/delete links to edit/delete a topic in the instructor view. These had to be conditionally added based on the role of the currently logged in user. This was to prevent students from editing/deleting topics and to keep instructors from signing up for a topic. This was implemented as follows.

Adding Edit/Delete functionality to topics tab

The current expertiza project had two views to display the Actions column in the topics table. These were _reserve_topics.html.erb and _actions.html. The first one was displaying the signup button for the student and the latter was displaying the bookmarks and rendering the _reserve_topics.html.erb after the bookmarks. On top of this we had to add the edit/delete links for the instructor. A refactor was called for. We decided to create a _all_actions.html.erb partial which had the responsibility to display the relevant actions depending upon the role of the currently logged in user. This helped us remove the separate partial to render actions pertaining to a student, namely _reserve_topics.html.erb . Also the _actions.html.erb only took care of displaying the bookmark links rather than dealing with both bookmarks and actions.

partial_view:_all_actions,html.erb

<% if ['Instructor', 'Teaching Assistant', 'Administrator', 'Super-Administrator'].include? current_user_role?.name %>
    <td align="center">
      <%= link_to image_tag('edit_icon.png', :border => 0, :title => 'Edit Topic', :align => 'middle'), :controller=>'sign_up_sheet', :action=> 'edit', :id => topic.id %>
      <%= link_to image_tag('delete_icon.png', :border => 0, :title => 'Delete Topic', :align => 'middle'), sign_up_sheet_path(topic.id), method: :delete, data: {confirm: 'Are you sure?'} %>
<%elsif @show_actions %> 
    ... 
    #Render signup button for student here. The @show_actions will be true if this partial is navigated from the SignupSheetController which is accessible only to students.

Case 2 : Cleaning up unused code

The Refactors mentioned above enable us to delete unused partials namely:

• assignments controller partials :
  • _add_signup_topics.html.erb
  • _reserve_topic.html.erb

• signup_sheet_controller partials :
  • _reserve_topic.html.erb

See Also

1. Expertiza on GitHub
2. GitHub Project Repository Fork
3. The live Expertiza website
4. VCL link - This might not be available after Nov. 2014
5. Expertiza project documentation wiki
6. The OSS project requirements doc (Fall 2014 - Expertiza)

References

Expertiza
Code Refactoring
Code smell