public static function selectForQuestion(CMA_Thread $thread)
 {
     $ids = $thread->getPostMeta(CMA_Thread::$_meta['attachment'], false);
     if (!empty($ids)) {
         return parent::select($thread->getId(), $ids);
     } else {
         return array();
     }
 }
 public static function selectForAnswer(CMA_Answer $answer)
 {
     $ids = get_comment_meta($answer->getId(), CMA_Answer::META_ATTACHMENT, false);
     if (!empty($ids)) {
         $result = parent::select($answer->getThreadId(), get_comment_meta($answer->getId(), CMA_Answer::META_ATTACHMENT, false));
         foreach ($result as $attachment) {
             $attachment->setAnswerId($answer->getId());
         }
         return $result;
     } else {
         return array();
     }
 }