Extract and generalize embedded attributes in serializers

app/serializers/board_serializer.rb

@@ -1,8 +1,15 @@
 class BoardSerializer
   include TalkSerializer
+  include EmbeddedAttributes
+
   all_attributes
   can_include :discussions, :parent, :sub_boards
   can_filter_by :subject_default
   can_sort_by :created_at
   self.default_sort = 'created_at'
+  self.eager_loads = [:project]
+
+  def custom_attributes
+    super.merge attributes_from :project
+  end
 end

app/serializers/comment_serializer.rb

@@ -1,5 +1,6 @@
 class CommentSerializer
   include TalkSerializer
+  include EmbeddedAttributes
   include ModerationActions
 
   all_attributes
@@ -17,29 +18,6 @@ def custom_attributes
       .merge focus: focus, user_display_name: model.user.display_name
   end
 
-  def discussion_attributes
-    %w(comments_count subject_default title updated_at users_count)
-  end
-
-  def board_attributes
-    %w(comments_count description discussions_count id parent_id subject_default title users_count)
-  end
-
-  def project_attributes
-    %w(slug)
-  end
-
-  def attributes_from(relation)
-    { }.tap do |attrs|
-      record_attributes = model.send(relation).attributes rescue { }
-      send("#{ relation }_attributes").each do |attr|
-        value = record_attributes[attr]
-        value = value.to_s if attr =~ /(_id)|(^id$)$/
-        attrs[:"#{ relation }_#{ attr }"] = value
-      end
-    end
-  end
-
   def focus
     focus_serializer.as_json model.focus
   rescue

app/serializers/concerns/embedded_attributes.rb

@@ -0,0 +1,26 @@
+module EmbeddedAttributes
+  extend ActiveSupport::Concern
+
+  def discussion_attributes
+    %w(comments_count subject_default title updated_at users_count)
+  end
+
+  def board_attributes
+    %w(comments_count description discussions_count id parent_id subject_default title users_count)
+  end
+
+  def project_attributes
+    %w(slug)
+  end
+
+  def attributes_from(relation)
+    { }.tap do |attrs|
+      record_attributes = model.send(relation).attributes rescue { }
+      send("#{ relation }_attributes").each do |attr|
+        value = record_attributes[attr]
+        value = value.to_s if attr =~ /(_id)|(^id$)$/
+        attrs[:"#{ relation }_#{ attr }"] = value
+      end
+    end
+  end
+end

app/serializers/discussion_serializer.rb

@@ -1,15 +1,19 @@
 class DiscussionSerializer
   include TalkSerializer
+  include EmbeddedAttributes
   include ModerationActions
 
   all_attributes
   can_include :comments, :board, :user
   can_filter_by :title, :subject_default, :sticky
   can_sort_by :updated_at, :sticky, :sticky_position
   self.default_sort = '-sticky,sticky_position,-updated_at'
-  self.eager_loads = [:user]
+  self.eager_loads = [:user, :board, :project]
 
   def custom_attributes
-    super.merge user_display_name: model.user.display_name
+    super
+      .merge(attributes_from(:project))
+      .merge(attributes_from(:board))
+      .merge user_display_name: model.user.display_name
   end
 end

spec/serializers/board_serializer_spec.rb

@@ -4,5 +4,6 @@
   it_behaves_like 'a talk serializer', exposing: :all, including: [:discussions, :parent, :sub_boards] do
     let(:parent){ create :board }
     let(:model_instance){ create :board_with_subboards, parent: parent }
+    it_behaves_like 'a serializer with embedded attributes', relations: [:project]
   end
 end

spec/serializers/comment_serializer_spec.rb

@@ -5,11 +5,8 @@
     let(:focus){ create :subject }
     let(:model_instance){ create :comment_for_focus, focus: focus }
     let(:json){ CommentSerializer.resource(id: model_instance.id)[:comments].first }
-    let!(:project) do
-      Project.find_by_id(model_instance.project_id) ||
-      create(:project, id: model_instance.project_id)
-    end
     subject{ json }
+    it_behaves_like 'a serializer with embedded attributes', relations: [:project, :discussion, :board]
 
     its([:user_display_name]){ is_expected.to eql model_instance.user.display_name }
     it{ is_expected.to include :focus }
@@ -27,29 +24,6 @@
       it{ is_expected.to have_key :updated_at }
       it{ is_expected.to have_key :project_id }
     end
-
-    describe '#board_attributes' do
-      its([:board_comments_count]){ is_expected.to eql model_instance.board.comments_count }
-      its([:board_description]){ is_expected.to eql model_instance.board.description }
-      its([:board_discussions_count]){ is_expected.to eql model_instance.board.discussions_count }
-      its([:board_id]){ is_expected.to eql model_instance.board.id.to_s }
-      its([:board_parent_id]){ is_expected.to eql model_instance.board.parent_id.to_s }
-      its([:board_subject_default]){ is_expected.to eql model_instance.board.subject_default }
-      its([:board_title]){ is_expected.to eql model_instance.board.title }
-      its([:board_users_count]){ is_expected.to eql model_instance.board.users_count }
-    end
-
-    describe '#discussion_attributes' do
-      its([:discussion_comments_count]){ is_expected.to eql model_instance.discussion.comments_count }
-      its([:discussion_subject_default]){ is_expected.to eql model_instance.discussion.subject_default }
-      its([:discussion_title]){ is_expected.to eql model_instance.discussion.title }
-      its([:discussion_updated_at]){ is_expected.to be_within(1.second).of model_instance.discussion.updated_at }
-      its([:discussion_users_count]){ is_expected.to eql model_instance.discussion.users_count }
-    end
-
-    describe '#project_attributes' do
-      its([:project_slug]){ is_expected.to eql model_instance.project.slug }
-    end
   end
 
   it_behaves_like 'a moderatable serializer' do

spec/serializers/discussion_serializer_spec.rb

@@ -3,11 +3,14 @@
 RSpec.describe DiscussionSerializer, type: :serializer do
   it_behaves_like 'a talk serializer', exposing: :all, including: [:comments, :board, :user] do
     subject{ json }
+    it_behaves_like 'a serializer with embedded attributes', relations: [:project, :board]
+
     its([:user_display_name]){ is_expected.to eql model_instance.user.display_name }
 
     describe '.default_sort' do
       let(:board){ create :board }
-      let!(:discussion1){ create :discussion, board: board, updated_at: 1.minute.ago.utc }
+      let!(:model_instance){ create :discussion, board: board, updated_at: 1.minute.ago.utc }
+      let(:discussion1){ model_instance }
       let!(:discussion2){ create :discussion, board: board, updated_at: 2.minutes.ago.utc }
       let!(:sticky1){ create :discussion, board: board, updated_at: 2.minute.ago.utc, sticky: true, sticky_position: 1 }
       let!(:sticky2){ create :discussion, board: board, updated_at: 1.minutes.ago.utc, sticky: true, sticky_position: 2 }

spec/support/shared_examples_for_embedded_attributes.rb

@@ -0,0 +1,40 @@
+require 'rspec'
+
+RSpec.shared_examples_for 'a serializer with embedded attributes' do |relations: []|
+  let!(:project) do
+    Project.find_by_id(model_instance.project_id) ||
+    create(:project, id: model_instance.project_id)
+  end
+
+  if relations.include?(:board)
+    describe '#board_attributes' do
+      subject{ json }
+      its([:board_comments_count]){ is_expected.to eql model_instance.board.comments_count }
+      its([:board_description]){ is_expected.to eql model_instance.board.description }
+      its([:board_discussions_count]){ is_expected.to eql model_instance.board.discussions_count }
+      its([:board_id]){ is_expected.to eql model_instance.board.id.to_s }
+      its([:board_parent_id]){ is_expected.to eql model_instance.board.parent_id.to_s }
+      its([:board_subject_default]){ is_expected.to eql model_instance.board.subject_default }
+      its([:board_title]){ is_expected.to eql model_instance.board.title }
+      its([:board_users_count]){ is_expected.to eql model_instance.board.users_count }
+    end
+  end
+
+  if relations.include?(:discussion)
+    describe '#discussion_attributes' do
+      subject{ json }
+      its([:discussion_comments_count]){ is_expected.to eql model_instance.discussion.comments_count }
+      its([:discussion_subject_default]){ is_expected.to eql model_instance.discussion.subject_default }
+      its([:discussion_title]){ is_expected.to eql model_instance.discussion.title }
+      its([:discussion_updated_at]){ is_expected.to be_within(1.second).of model_instance.discussion.updated_at }
+      its([:discussion_users_count]){ is_expected.to eql model_instance.discussion.users_count }
+    end
+  end
+
+  if relations.include?(:project)
+    describe '#project_attributes' do
+      subject{ json }
+      its([:project_slug]){ is_expected.to eql model_instance.project.slug }
+    end
+  end
+end