title: how to return an array of serialized objects via Active Model Serializer
body: <p>I have a user who has a list of liked items. I'd like to create a serializer that returns this. For a single items, I would have something like this:</p>
  
  <pre><code>class UserProfileSerializer &lt; ActiveModel::Serializer
    attributes :id, :name, :liked_items2
  
    def liked_items2
      ItemLikedSerializer.new(object.liked_items).attributes
    end
  end
  </code></pre>
  
  <p>but how would I return an array of liked items and apply ItemLikedSerializer to it?</p>