return depth of comment

models/comment.rb

@@ -42,6 +42,7 @@ class Comment < Content
       as_document.slice(*%w[body course_id endorsed created_at updated_at])
                   .merge("id" => _id)
                   .merge("user_id" => (author.id if author))
+                  .merge("depth" => depth)
                   .merge("thread_id" => comment_thread.id)
                   .merge("votes" => votes.slice(*%w[count up_count down_count point]))
     end

spec/api/comment_spec.rb

@@ -14,6 +14,7 @@ describe "app" do
         retrieved["id"].should == comment.id.to_s
         retrieved["children"].should be_nil
         retrieved["votes"]["point"].should == comment.votes_point
+        retrieved["depth"].should == comment.depth
       end
       it "retrieve information of a single comment with its sub comments" do
         comment = Comment.first