title: Merge and sort results from two entities in Symfony controller
body: <p>I would like to get the ten most recent entries between two entities (post, news).</p>
  
  <p>In my controller:</p>
  
  <pre><code>$posts = $em-&gt;getRepository('AcmePostBundle:Post')-&gt;getTenLatest();
  
  $news = $em-&gt;getRepository('AcmeNewsBundle:News')-&gt;getTenLatest();
  </code></pre>
  
  <p>How do I merge the two results? Something like:</p>
  
  <pre><code>$latest = $posts-&gt;merge($news);
  </code></pre>
  
  <p>And then, sort them by a date field, limit 10?</p>