/**
  * add comment
  */
 public function add()
 {
     if ($this->isPost()) {
         $uid = $this->user['uid'];
         if (empty($uid)) {
             Message::showError('please login');
         }
         $content = trim($_POST['content']);
         if (empty($content)) {
             Message::showError('content is empty');
         }
         if (!is_numeric($_POST['order_id']) || !is_numeric($_POST['item_id']) || !is_numeric($_POST['star']) || !is_numeric($_POST['parent_id'])) {
             Message::showError('parameters is not number');
         }
         $order_id = trim($_POST['order_id']);
         $item_id = trim($_POST['item_id']);
         $star = trim($_POST['star']);
         $parent_id = trim($_POST['parent_id']);
         $commentModel = new CommentModel();
         $result = $commentModel->add($uid, $content, $star, $order_id, $item_id, $parent_id);
         if (!empty($result)) {
             Message::showSucc('add comment success');
         } else {
             Message::showError('add comment failed');
         }
     }
     $this->display('comment.html');
 }