Split MR widget into cached and non-cached serializers

Splits auto-refreshing of MR widget into 2 requests:

- the one which uses etag-caching and invalidates the fields on change
- the one without caching

The idea is to gradually move all the fields to etag-cached endpoint

1 files changed, 20 insertions, 3 deletions

diff --git a/app/controllers/projects/merge_requests/content_controller.rb b/app/controllers/projects/merge_requests/content_controller.rb
index 6e026b83ee3..eec5c1a4355 100644
--- a/app/controllers/projects/merge_requests/content_controller.rb
+++ b/app/controllers/projects/merge_requests/content_controller.rb
@@ -7,16 +7,33 @@ class Projects::MergeRequests::ContentController < Projects::MergeRequests::Appl
   # for other types of serialization
 
   before_action :close_merge_request_if_no_source_project
+  before_action :set_polling_header
   around_action :allow_gitaly_ref_name_caching
 
   def widget
     respond_to do |format|
       format.json do
-        Gitlab::PollingInterval.set_header(response, interval: 10_000)
+        render json: serializer(MergeRequestPollWidgetEntity)
+      end
+    end
+  end
 
-        serializer = MergeRequestSerializer.new(current_user: current_user, project: merge_request.project)
-        render json: serializer.represent(merge_request, serializer: 'widget')
+  def cached_widget
+    respond_to do |format|
+      format.json do
+        render json: serializer(MergeRequestPollCachedWidgetEntity)
       end
     end
   end
+
+  private
+
+  def set_polling_header
+    Gitlab::PollingInterval.set_header(response, interval: 10_000)
+  end
+
+  def serializer(entity)
+    serializer = MergeRequestSerializer.new(current_user: current_user, project: merge_request.project)
+    serializer.represent(merge_request, {}, entity)
+  end
 end