function retrieve($url)
 {
     //### FIXME: temp hack to get file list into 'single' record without changing database
     $result = parent::retrieve($url);
     if ($url == '/test/single' && !is_null($result)) {
         $result['media'] = array(array('title' => 'Test MP3', 'location' => 'file1.mp3', 'content_type' => 'audio/mpeg'));
     }
     return $result;
 }