/**
  * Gets post order by field values
  *
  * @return array
  */
 public static function getPostOrderByFields()
 {
     $keys = array('ID', 'author', 'title', 'name', 'date', 'modified', 'parent', 'rand', 'menu_order', 'meta_value');
     if (meAnjanWqg_Utils::isMinWpVersion('2.8')) {
         $keys[] = 'none';
         $keys[] = 'meta_value_num';
     }
     if (meAnjanWqg_Utils::isMinWpVersion('2.9')) {
         $keys[] = 'comment_count';
     }
     if (meAnjanWqg_Utils::isMinWpVersion('3.5')) {
         $keys[] = 'post__in';
     }
     if (meAnjanWqg_Utils::isMinWpVersion('4.0')) {
         $keys[] = 'type';
     }
     asort($keys);
     return $keys;
 }