在cakephp中查看帖子时如何保存到数据库

Question

请在cakephp中查看帖子时如何保存到数据库。我有一个通知系统，我很乐意将帖子标记为“阅读”。我该如何实现这一目标？ 这是我的观点代码：

public function view($id = null) {
    if (!$this->Notification->exists()) {
        throw new NotFoundException(__('Invalid notification'));
    }elseif{
        $this->request->data['Notification']['is_read'] = 1;
         $this->Notification->save($this->request->data);
        $this->Session->setFlash(__('The notification has been deleted.'));
    }
    $options = array('conditions' => array('Notification.' . $this->Notification->primaryKey => $id));
    $this->set('notification', $this->Notification->find('first', $options));

}

此代码的问题在于，当第二次查看帖子时，它会一直保存。我怎么可能实现这种能力。