Add live dashboard for teachers in the context of an exercise

This commit also adds the fundamentals for ActionCable

app/assets/javascripts/application.js

@@ -14,6 +14,8 @@
 //= require turbolinks
 //= require pagedown_bootstrap
 //= require d3
+//= require rails-timeago
+//= require locales/jquery.timeago.de.js
 //
 // lib/assets
 //= require flash

app/assets/javascripts/base.js

@@ -23,3 +23,9 @@ $.fn.scrollTo = function(selector) {
     scrollTop: $(selector).offset().top - $(this).offset().top + $(this).scrollTop()
   }, ANIMATION_DURATION);
 };
+
+$.fn.replaceWithPush = function(a) {
+    const $a = $(a);
+    this.replaceWith($a);
+    return $a;
+};

app/assets/javascripts/cable.js

@@ -0,0 +1,13 @@
+// Action Cable provides the framework to deal with WebSockets in Rails.
+// You can generate new channels where WebSocket features live using the `rails generate channel` command.
+//
+//= require action_cable
+//= require_self
+//= require_tree ./channels
+
+(function() {
+  this.App || (this.App = {});
+
+  App.cable = ActionCable.createConsumer();
+
+}).call(this);

app/assets/javascripts/channels/la_exercises.js

@@ -0,0 +1,33 @@
+$(document).on('turbolinks:load', function() {
+    if ($.isController('exercises') && $('.teacher_dashboard').isPresent()) {
+
+        const exercise_id = $('.teacher_dashboard').data().exerciseId;
+        const study_group_id = $('.teacher_dashboard').data().studyGroupId;
+
+        const specific_channel = { channel: "LaExercisesChannel", exercise_id: exercise_id, study_group_id: study_group_id };
+
+
+        App.la_exercise = App.cable.subscriptions.create(specific_channel, {
+            connected: function () {
+                // Called when the subscription is ready for use on the server
+            },
+
+            disconnected: function () {
+                // Called when the subscription has been terminated by the server
+            },
+
+            received: function (data) {
+                // Called when there's incoming data on the websocket for this channel
+                let $row = $('tr[data-id="' + data.id + '"]');
+                if ($row.length === 0) {
+                    $row = $($('#posted_rfcs')[0].insertRow(0));
+                }
+                $row = $row.replaceWithPush(data.html);
+                $row.find('time').timeago();
+                $row.click(function () {
+                    Turbolinks.visit($(this).data("href"));
+                });
+            }
+        });
+    }
+});

app/assets/stylesheets/base.css.scss

@@ -113,3 +113,7 @@ span.caret {
     -webkit-transform: perspective(120px) rotateX(-180deg) rotateY(-179.9deg);
   }
 }
+
+.table-row-clickable {
+  cursor: pointer;
+}

app/channels/application_cable/channel.rb

@@ -0,0 +1,4 @@
+module ApplicationCable
+  class Channel < ActionCable::Channel::Base
+  end
+end

app/channels/application_cable/connection.rb

@@ -0,0 +1,30 @@
+module ApplicationCable
+  class Connection < ActionCable::Connection::Base
+    identified_by :current_user
+
+    def connect
+      self.current_user = find_verified_user
+    end
+
+    def disconnect
+      # Any cleanup work needed when the cable connection is cut.
+    end
+
+    private
+
+    def session
+      # `session` is not available here, so that we need to use `cookies.encrypted` instead
+      cookies.encrypted[Rails.application.config.session_options[:key]].symbolize_keys
+    end
+
+    def find_verified_user
+      # Finding the current_user is similar to the code used in application_controller.rb#current_user
+      current_user = ExternalUser.find_by(id: session[:external_user_id]) || InternalUser.find_by(id: session[:user_id])
+      if current_user
+        current_user
+      else
+        reject_unauthorized_connection
+      end
+    end
+  end
+end

app/channels/la_exercises_channel.rb

@@ -0,0 +1,16 @@
+class LaExercisesChannel < ApplicationCable::Channel
+
+  def subscribed
+    stream_from specific_channel
+  end
+
+  def unsubscribed
+    stop_all_streams
+  end
+
+  private
+  def specific_channel
+    reject unless StudyGroupPolicy.new(current_user, StudyGroup.find_by(id: params[:study_group_id])).stream_la?
+    "la_exercises_#{params[:exercise_id]}_channel_study_group_#{params[:study_group_id]}"
+  end
+end

app/controllers/exercises_controller.rb

@@ -7,7 +7,7 @@ class ExercisesController < ApplicationController
 
   before_action :handle_file_uploads, only: [:create, :update]
   before_action :set_execution_environments, only: [:create, :edit, :new, :update]
-  before_action :set_exercise_and_authorize, only: MEMBER_ACTIONS + [:clone, :implement, :working_times, :intervention, :search, :run, :statistics, :submit, :reload, :feedback]
+  before_action :set_exercise_and_authorize, only: MEMBER_ACTIONS + [:clone, :implement, :working_times, :intervention, :search, :run, :statistics, :submit, :reload, :feedback, :study_group_dashboard]
   before_action :set_external_user_and_authorize, only: [:statistics]
   before_action :set_file_types, only: [:create, :edit, :new, :update]
   before_action :set_course_token, only: [:implement]
@@ -475,4 +475,13 @@ class ExercisesController < ApplicationController
     end
   end
 
+  def study_group_dashboard
+    authorize!
+    @study_group_id = params[:study_group_id]
+    @request_for_comments = RequestForComment.
+            where(exercise: @exercise).includes(:submission).
+            where(submissions: {study_group_id: @study_group_id}).
+            order(created_at: :desc)
+  end
+
 end

app/controllers/request_for_comments_controller.rb

@@ -143,7 +143,7 @@ class RequestForCommentsController < ApplicationController
     # Never trust parameters from the scary internet, only allow the white list through.
     def request_for_comment_params
       # The study_group_id might not be present in the session (e.g. for internal users), resulting in session[:study_group_id] = nil which is intended.
-      params.require(:request_for_comment).permit(:exercise_id, :file_id, :question, :requested_at, :solved, :submission_id).merge(user_id: current_user.id, user_type: current_user.class.name, study_group_id: session[:study_group_id])
+      params.require(:request_for_comment).permit(:exercise_id, :file_id, :question, :requested_at, :solved, :submission_id).merge(user_id: current_user.id, user_type: current_user.class.name)
     end
 
     def comment_params

app/controllers/submissions_controller.rb

@@ -201,6 +201,8 @@ class SubmissionsController < ApplicationController
     save_run_output
 
     if @run_output.blank?
+      @raw_output ||= ''
+      @run_output ||= ''
       parse_message t('exercises.implement.no_output', timestamp: l(Time.now, format: :short)), 'stdout', tubesock
     end
 

app/helpers/action_cable_helper.rb

@@ -0,0 +1,15 @@
+module ActionCableHelper
+  def trigger_rfc_action_cable
+    if submission.study_group_id.present?
+      ActionCable.server.broadcast(
+        "la_exercises_#{exercise_id}_channel_study_group_#{submission.study_group_id}",
+        id: id,
+        html: (ApplicationController.render(partial: 'request_for_comments/list_entry',
+                                            locals: {request_for_comment: self})))
+    end
+  end
+
+  def trigger_rfc_action_cable_from_comment
+    RequestForComment.find_by(submission: file.context).trigger_rfc_action_cable
+  end
+end

app/models/comment.rb

@@ -1,8 +1,12 @@
 class Comment < ApplicationRecord
   # inherit the creation module: encapsulates that this is a polymorphic user, offers some aliases and makes sure that all necessary attributes are set.
   include Creation
+  include ActionCableHelper
+
   attr_accessor :username, :date, :updated, :editable
 
   belongs_to :file, class_name: 'CodeOcean::File'
   belongs_to :user, polymorphic: true
+
+  after_save :trigger_rfc_action_cable_from_comment
 end

app/models/request_for_comment.rb

@@ -1,5 +1,7 @@
 class RequestForComment < ApplicationRecord
   include Creation
+  include ActionCableHelper
+
   belongs_to :submission
   belongs_to :exercise
   belongs_to :file, class_name: 'CodeOcean::File'
@@ -10,6 +12,8 @@ class RequestForComment < ApplicationRecord
   scope :unsolved, -> { where(solved: [false, nil]) }
   scope :in_range, -> (from, to) { where(created_at: from..to) }
 
+  after_save :trigger_rfc_action_cable
+
     def self.last_per_user(n = 5)
       from("(#{row_number_user_sql}) as request_for_comments")
           .where("row_number <= ?", n)

app/policies/exercise_policy.rb

@@ -3,8 +3,8 @@ class ExercisePolicy < AdminOrAuthorPolicy
     admin?
   end
 
-  def show?
-    admin? || teacher?
+  [:show?, :study_group_dashboard?].each do |action|
+    define_method(action) { admin? || teacher? }
   end
 
   [:clone?, :destroy?, :edit?, :statistics?, :update?, :feedback?].each do |action|

app/policies/study_group_policy.rb

@@ -3,8 +3,8 @@ class StudyGroupPolicy < AdminOnlyPolicy
     admin? || teacher?
   end
 
-  [:show?, :destroy?, :edit?, :update?].each do |action|
-    define_method(action) { admin? || @user.teacher? && @record.users.include?(@user) }
+  [:show?, :destroy?, :edit?, :update?, :stream_la?].each do |action|
+    define_method(action) { admin? || @user.teacher? && @record.present? && @record.users.include?(@user) }
   end
 
   class Scope < Scope

app/views/exercises/study_group_dashboard.html.slim

@@ -0,0 +1,21 @@
+h1
+  = t('.live_dashboard')
+
+div.teacher_dashboard data-exercise-id="#{@exercise.id}" data-study-group-id="#{@study_group_id}"
+
+h4
+  = t('.related_requests_for_comments')
+
+.table-responsive
+  table.table.table-hover.mt-4
+    thead
+      tr
+        th.text-center
+          i.mr-0 class="fa fa-lightbulb-o" aria-hidden="true" title = t('request_for_comments.solved')
+        th.text-center
+          i.mr-0 class="fa fa-comment" aria-hidden="true" title = t('request_for_comments.comments') align="center"
+        th.col-12 = t('activerecord.attributes.request_for_comments.question')
+        th = t('activerecord.attributes.request_for_comments.username')
+        th.text-nowrap = t('activerecord.attributes.request_for_comments.requested_at')
+      tbody#posted_rfcs
+        = render(partial: 'request_for_comments/list_entry', collection: @request_for_comments, as: :request_for_comment)

app/views/layouts/application.html.slim

@@ -5,6 +5,7 @@ html lang='en'
     meta name='viewport' content='width=device-width, initial-scale=1'
     title = application_name
     link href=asset_path('favicon.png') rel='icon' type='image/png'
+    = action_cable_meta_tag
     = stylesheet_pack_tag('application', media: 'all', 'data-turbolinks-track': true)
     = stylesheet_pack_tag('stylesheets', media: 'all', 'data-turbolinks-track': true)
     = stylesheet_link_tag('application', media: 'all', 'data-turbolinks-track': true)
@@ -12,6 +13,7 @@ html lang='en'
     = javascript_include_tag('application', 'data-turbolinks-track': true)
     = yield(:head)
     = csrf_meta_tags
+    = timeago_script_tag
   body
     - unless @embed_options[:hide_navbar]
       nav.navbar.navbar-dark.bg-dark.navbar-expand-md.mb-4.py-1 role='navigation'

app/views/request_for_comments/_list_entry.html.slim

@@ -0,0 +1,15 @@
+tr.table-row-clickable data-id=request_for_comment.id data-href=request_for_comment_path(request_for_comment)
+  td.p-2
+    - if request_for_comment.solved?
+      span.fa.fa-check.fa-2x.text-success aria-hidden="true"
+    - elsif request_for_comment.full_score_reached
+      span.fa.fa-check.fa-2x style="color:darkgrey" aria-hidden="true"
+    - else
+      = ''
+  td.text-center = request_for_comment.comments_count
+  - if request_for_comment.has_attribute?(:question) && request_for_comment.question.present?
+    td.text-primary = truncate(request_for_comment.question, length: 200)
+  - else
+    td.text-black-50.font-italic = t('request_for_comments.no_question')
+  td = request_for_comment.user
+  td = timeago_tag request_for_comment.created_at