title: Restrict specific fields in the response of rails controller
body: <p>I have a controller action like</p>
  
  <pre><code>def index
    @videos =  Video.all.to_a
  
    respond_to do |format|
      format.xml  { render :xml =&gt; @videos }
      format.json { render :json =&gt; @videos }
    end
  end
  </code></pre>
  
  <p>Video has attributes <code>name</code> and <code>title</code>.</p>
  
  <p>I want the return xml to contain only <code>title</code>.</p>
  
  <p>How do I restrict it from the response.</p>