Return discussion object from NotesController#create when return_discussion param is set

app/assets/javascripts/diffs/store/utils.js

@@ -55,6 +55,7 @@ export function getNoteFormData(params) {
     note_project_id: '',
     target_type: noteableData.targetType,
     target_id: noteableData.id,
+    return_discussion: 'true',
     note: {
       note,
       position,

app/controllers/concerns/notes_actions.rb

@@ -43,12 +43,26 @@ module NotesActions
 
     @note = Notes::CreateService.new(note_project, current_user, create_params).execute
 
-    if @note.is_a?(Note)
-      prepare_notes_for_rendering([@note], noteable)
+    respond_to do |format|
+      format.json do
+        json = {
+          commands_changes: @note.commands_changes
+        }
+
+        if @note.persisted? && return_discussion?
+          json[:valid] = true
+
+          discussion = @note.discussion
+          prepare_notes_for_rendering(discussion.notes)
+          json[:discussion] = discussion_serializer.represent(discussion, context: self)
+        else
+          prepare_notes_for_rendering([@note])
+
+          json.merge!(note_json(@note))
         end
 
-    respond_to do |format|
-      format.json { render json: note_json(@note) }
+        render json: json
+      end
       format.html { redirect_back_or_default }
     end
   end
@@ -57,10 +71,7 @@ module NotesActions
   # rubocop:disable Gitlab/ModuleWithInstanceVariables
   def update
     @note = Notes::UpdateService.new(project, current_user, note_params).execute(note)
-
-    if @note.is_a?(Note)
     prepare_notes_for_rendering([@note])
-    end
 
     respond_to do |format|
       format.json { render json: note_json(@note) }
@@ -91,14 +102,17 @@ module NotesActions
   end
 
   def note_json(note)
-    attrs = {
-      commands_changes: note.commands_changes
-    }
+    attrs = {}
 
     if note.persisted?
       attrs[:valid] = true
 
-      if use_note_serializer?
+      if return_discussion?
+        discussion = note.discussion
+        prepare_notes_for_rendering(discussion.notes)
+
+        attrs[:discussion] = discussion_serializer.represent(discussion, context: self)
+      elsif use_note_serializer?
         attrs.merge!(note_serializer.represent(note))
       else
         attrs.merge!(
@@ -218,6 +232,10 @@ module NotesActions
     ProjectNoteSerializer.new(project: project, noteable: noteable, current_user: current_user)
   end
 
+  def discussion_serializer
+    DiscussionSerializer.new(project: project, noteable: noteable, current_user: current_user, note_entity: ProjectNoteEntity)
+  end
+
   def note_project
     strong_memoize(:note_project) do
       next nil unless project
@@ -237,6 +255,10 @@ module NotesActions
     end
   end
 
+  def return_discussion?
+    Gitlab::Utils.to_boolean(params[:return_discussion])
+  end
+
   def use_note_serializer?
     return false if params['html']
 

spec/controllers/projects/notes_controller_spec.rb

@@ -207,6 +207,14 @@ describe Projects::NotesController do
       expect(response).to have_gitlab_http_status(200)
     end
 
+    it 'returns discussion JSON when the return_discussion param is set' do
+      post :create, request_params.merge(format: :json, return_discussion: 'true')
+
+      expect(response).to have_gitlab_http_status(200)
+      expect(json_response).to have_key 'discussion'
+      expect(json_response['discussion']['notes'][0]['note']).to eq(request_params[:note][:note])
+    end
+
     context 'when merge_request_diff_head_sha present' do
       before do
         service_params = {