title: One action in Rails controller sends no data back
body: <p>So I have these two actions in my <code>RelationshipController</code>:</p>
  
  <pre><code>class RelationshipsController &lt; ApplicationController
      before_filter :authenticate_user!
      respond_to :json
  
      def create
          user = User.find(params[:user_to_follow_id])
          relationship = current_user.follow!(user)
          respond_with user
      end
  
      def destroy
          user = User.find(params[:id])
          current_user.unfollow!(user)
          logger.debug user.id
          respond_with user
      end
  end
  </code></pre>
  
  <p>Now when I use the create action, I get a response back with the <code>respond_with user</code> method which is also nicely formatted with <code>ActiveModel::Serializer</code>.</p>
  
  <p>When I use the destroy method, I get a response back which is completely blank. It does seems to work with <code>render json: {user: user, status: 201}</code> but I am wondering why am I not able to use <code>respond_with</code> for both of them? The user they send back has the same type of data in both cases.</p>
  
  <p>Unfollow method:</p>
  
  <pre><code>def unfollow!(user)
          $redis.multi do
              $redis.srem(self.redis_key(:following), user.id)
              $redis.srem(user.redis_key(:followers), self.id)
          end
  end
  </code></pre>