gistfile1.aw

public static function getSubTopicIdsOfTopic($topicId, &$topics = null) 
{
  $list = array();
  if (empty($topics))
    $topics = PTopic::model()->findAll();
  foreach ($topics as $key => $topic) {
    if ($topic->parentId == $topicId) {
      $list[] = $topic->id;
      $list = array_merge($list, self::getSubTopicIdsOfTopic($topic->id, $topics));
    }
  }
    
  return $list;
}