title: How to build following to_json in JBuilder?
body: <p>I have method in my model</p>
  
  <pre><code>def indexed_json
    to_json(
      only: [:id, :chanell_id, :title],
      include: [
        :locations,
        {categories: {only: [:name, :id]}}
      ]
    )
  end
  </code></pre>
  
  <p>I would like to rewrite that in JBuilder and also add another attribute: <code>type_name: self.class.name</code></p>