CSC/ECE 517 Fall 2015/oss E1559 rrz

E1559: Refactoring JoinTeamRequestsController and InvitationController classes

This page gives a breif description on the expertiza based oss project that aimed at refactoring join_team_request_controller.rb and invitation_controller.rb files so that they follow the DRY principle and Ruby on Rails coding practices.

Code Refactoring

Code refactoring is process of changing the code to make it more maintainable, without changing the functionality of the code. Some of the reasons for performing refactoring are:

• To remove duplicate code.
• To make the code more maintainable.
• To divide functionality of the class

Introduction to Expertiza

Expertiza is a web application where students can submit and review learning objects like code, writings, etc. It gives scope for creation of reusable learning objects. Students submit assignments, which can than graded through peer reviews. The Expertiza project is supported by the National Science Foundation.

Problem Statement

Classes involved

JoinTeamRequestsController and InvitationController

What the controller does

invitation_controller.rb is used by a user to invite other users to join his/her team. It performs validation before creating a request. Following chunk of code checks whether the user is allowed to get the invite or not.

   def action_allowed? # user specified only have access to the functionality of the controller
   ['Student', 'Instructor', 'Teaching Assistant'].include?(current_role_name)
   end

Now, invited user can accept or reject the request. Once the user has accepted the request, he can be seen as a part of the team.

join_team_requests_controller.rb is used when user decides to join a team. This is achieved by creating an advertisement for the team. Once the advertisement is created, it is shown in the Topic Selection section. The user who wants to join the team can send a "Request" to the members of the team. The members can then decide whether to send him/her an invite or decline the request.

What's wrong with the code

The invitation_controller.rb is doing the required task but it is difficult to understand the code, hence it becomes difficult to maintain the code. And the functions in the accept and create method can be broken down into separate methods.

In join_team_request_controller.rb has duplicate code in various methods which can be removed by creating a separate method for this common code.

What needs to be done

invitation_controller.rb

• Rename to Invitations_Controller.rb, as is not in accordance with current naming convention.
• Add comments explaining what each method does, and comments on how important variables are used as currently there are no comments.
• Refactor create and accept methods. Shorten and clarify them by adding private methods, as create and accept methods currently have a lot of code.
• Change the find_by_sql call(s) to Rails (Active Record) statements.
• Make sure that it can be used by a user with a TA or instructor account, if they are participating in this assignment.
• Change grammatically wrong or awkward flash messages.

join_team_requests_controller.rb

• Add comments to the code.
• Remove duplicate code.
• Update create and accept method to share code.
• Decline and destroy method should check for successful operation before returning.
• Change grammatically wrong or awkward flash messages.

Implementation

Renamed invitation_controller.rb to invitations_controller.rb

The controller renaming had to be incorporated in different files of the project. The table contain the file names along with the lines before and after the changes.

File Name	Line no.	Before	After
config/routes.rb	160	resources :invitation do	resources :invitations do
config/routes.rb	170	resources :join_team_requests do collection do get :edit end end	resources :join_team_requests do collection do post :decline get :edit end end
app/views/join_team_requests/_list_received.html.erb	33	<%= form_tag :controller => 'invitation', :action => 'create' do %>	<%= form_tag :controller => 'invitations', :action => 'create' do %>
app/views/student_teams/view.html.erb	151	{:controller => 'invitation', :action => 'cancel', :inv_id => inv.id, :student_id => @student.id} %>	{:controller => 'invitations', :action => 'cancel', :inv_id => inv.id, :student_id => @student.id} %>
app/views/student_teams/view.html.erb	193	{:controller => 'invitation', :action => 'accept', :inv_id => inv.id, :student_id => @student.id, :team_id => @team_id},	{:controller => 'invitations', :action => 'accept', :inv_id => inv.id, :student_id => @student.id, :team_id => @team_id},
app/views/student_teams/view.html.erb	198	{:controller => 'invitation', :action => 'decline', :inv_id => inv.id, :student_id => @student.id} %>	{:controller => 'invitations', :action => 'decline', :inv_id => inv.id, :student_id => @student.id} %>
app/views/student_teams/view.html.erb	217	<%= form_tag :controller => 'invitation', :action => 'create' do %>	<%= form_tag :controller => 'invitations', :action => 'create' do %>
app/controllers/invitations_controller.rb	1	class InvitationController < ApplicationController	class InvitationsController < ApplicationController

InvitationController.rb create and accept methods refactored

Before

After

def create user = User.find_by_name(params[:user][:name].strip) team = AssignmentTeam.find(params[:team_id]) student = AssignmentParticipant.find(params[:student_id]) return unless current_user_id?(student.user_id) #check if the invited user is valid if !user flash[:note] = "\"#{params[:user][:name].strip}\" does not exist. Please make sure the name entered is correct." else participant= AssignmentParticipant.where('user_id =? and parent_id =?', user.id, student.parent_id).first #check if the user is a participant of the assignment if !participant flash[:note] = "\"#{params[:user][:name].strip}\" is not a participant of this assignment." elsif team.full? flash[:error] = "Your team already has max members." else team_member = TeamsUser.where(['team_id =? and user_id =?', team.id, user.id]) #check if invited user is already in the team if (team_member.size > 0) flash[:note] = "\"#{user.name}\" is already a member of team." else #check if the invited user is already invited (i.e. awaiting reply) if Invitation.is_invited?(student.user_id, user.id, student.parent_id) @invitation = Invitation.new @invitation.to_id = user.id @invitation.from_id = student.user_id @invitation.assignment_id = student.parent_id @invitation.reply_status = 'W' @invitation.save else flash[:note] = "You have already sent an invitation to \"#{user.name}\"." end end end end def accept @inv = Invitation.find(params[:inv_id]) student = Participant.find(params[:student_id]) assignment_id=@inv.assignment_id inviter_user_id=@inv.from_id inviter_participant = AssignmentParticipant.find_by_user_id_and_assignment_id(inviter_user_id,assignment_id) ready_to_join=false #check if the inviter's team is still existing, and have available slot to add the invitee inviter_assignment_team = AssignmentTeam.team(inviter_participant) if inviter_assignment_team.nil? flash[:error]= "The team which invited you does not exist any more." else if inviter_assignment_team.full? flash[:error]= "The team which invited you is full now." else ready_to_join=true end end

def create #adds the new invitation to the table if Invitation.is_invited?(@student.user_id, @user.id, @student.parent_id) set_invitation(@user.id,@student.user_id,@student.parent_id,'W') #'W states the invitation is waitlisted, still not accepted' else flash[:note] = @@messages[:already_invited] end update_join_team_request @user,@student redirect_to view_student_teams_path student_id: @student.id end def update_join_team_request(user,student) #update the status in the join_team_request to A if user && student participant= AssignmentParticipant.where(['user_id =? and parent_id =?', user.id, student.parent_id]).first if participant old_entry = JoinTeamRequest.where(['participant_id =? and team_id =?', participant.id,params[:team_id]]).first if old_entry old_entry.update_attribute("status",'A') # 'A' states that the invitation has been accepted end end end end def auto_complete_for_user_name # searches the user name in the user table for auto complete search = params[:user][:name].to_s User.where(User.arel_table[:name].matches("%#{search}%")) #@users = User.find_by_sql("select * from users where LOWER(name) LIKE '%"+search+"%'") unless search.blank? end def accept # allows accepting of the invitation @inv = Invitation.find(params[:inv_id]) student = Participant.find(params[:student_id]) assignment_id=@inv.assignment_id inviter_user_id=@inv.from_id inviter_participant = AssignmentParticipant.find_by_user_id_and_assignment_id(inviter_user_id,assignment_id) #check if the inviter's team is still existing, and have available slot to add the invitee inviter_assignment_team = AssignmentTeam.team(inviter_participant) if inviter_assignment_team.nil? flash[:error]= @@messages[:invitation_not_exist] elsif inviter_assignment_team.full? flash[:error]= @@messages[:full_team] else @inv.reply_status = 'A' @inv.save #Remove the users previous team since they are accepting an invite for possibly a new team. TeamsUser.remove_team(student.user_id, params[:team_id]) #Accept the invite and return boolean on whether the add was successful add_successful = Invitation.accept_invite(params[:team_id], @inv.from_id, @inv.to_id, student.parent_id) unless add_successful flash[:error] = @@messages[:fail_to_add] end end redirect_to view_student_teams_path student_id: params[:student_id] end

InvitationController.rb Change the find_by_sql call(s) to Rails (Active Record) statements.

Before	After
@users = User.find_by_sql("select * from users where LOWER(name) LIKE '%"+search+"%'") unless search.blank?	User.where(User.arel_table[:name].matches("%#{search}%"))

InvitationController.rb changed to allow TA and instructor to be a part of a team

Before	After
def action_allowed? current_role_name.eql?("Student") end	def action_allowed? # user specified only have access to the functionality of the controller ['Student', 'Instructor', 'Teaching Assistant'].include?(current_role_name) end

JoinTeamRequestController.rb removed duplicate code

Before	After
def index @join_team_requests = JoinTeamRequest.all respond_to do |format| format.html # index.html.erb format.xml { render :xml => @join_team_requests } end	def index @join_team_request = JoinTeamRequest.all render_request # index.html.erb end
def show # searches the join team requests for a particular id @join_team_request = JoinTeamRequest.find(params[:id]) respond_to do |format| format.html # show.html.erb format.xml { render :xml => @join_team_request } end end def new # create a new join team request entry instance @join_team_request = JoinTeamRequest.new respond_to do |format| format.html # new.html.erb format.xml { render :xml => @join_team_request } end end	private def render_request respond_to do |format| format.html format.xml { render :xml => @join_team_request } end end def show # searches the join team requests for a particular id @join_team_request = JoinTeamRequest.find(params[:id]) render_request # show.html.erb end def new # create a new join team request entry instance @join_team_request = JoinTeamRequest.new render_request # new.html.erb end