controllers: refactor only param includes.

Add extra includes needed by the `only` param inside `respond_with`.

app/controllers/artist_commentaries_controller.rb

@@ -3,7 +3,9 @@ class ArtistCommentariesController < ApplicationController
   before_action :member_only, only: [:create_or_update, :revert]
 
   def index
-    @commentaries = ArtistCommentary.paginated_search(params).includes(model_includes(params))
+    @commentaries = ArtistCommentary.paginated_search(params)
+    @commentaries = @commentaries.includes(post: :uploader) if request.format.html?
+
     respond_with(@commentaries)
   end
 
@@ -36,14 +38,6 @@ class ArtistCommentariesController < ApplicationController
 
   private
 
-  def default_includes(params)
-    if ["json", "xml"].include?(params[:format])
-      []
-    else
-      [{post: [:uploader]}]
-    end
-  end
-
   def commentary_params
     params.fetch(:artist_commentary, {}).except(:post_id).permit(%i[
       original_description original_title translated_description translated_title