title: Limit Attributes in Controller
body: <p>i want to limit the attributes of "Promo" like i ust want to show the id and the title of promo
  My code is:</p>
  
  <pre><code>  def show
  if @job.present?
    if poster_authorize(@job)
    render json: @job, :include =&gt; [:tasks, :promo.as_json(only: [:title])], status: 200
    else
      json_forbidden("Forbidden")
    end
  else
    json_not_found("Job Not Available")
  end
  end
  </code></pre>