public function executeTag()
  {
    $this->book = sfDoctrine::queryFrom('Book')->from('Book.Tags')->where('Book.id = ? ',array($this->getRequestParameter('id'),false))->execute()->getFirst();
    $this->tags = sfDoctrine::queryFrom('Tag')->where('Tag.is_private = ?',false)->orderby('Tag.name')->execute();

    if($this->getRequest()->getMethod() == sfRequest::POST)
    {
        $this->book = sfDoctrine::queryFrom('Book')->where('Book.id = ? ',array($this->getRequestParameter('id'),false))->execute()->getFirst();
        
        $tags = $this->getRequestParameter('tags');
        sfLogger::getInstance()->debug('Type: '.gettype($tags));
        foreach($tags as $tag)
        {
            foreach($this->tags as $t_obj)
            {
            	if($t_obj->get('id')==$tag)
                {
                    $this->book->Tags[] = $t_obj;
                    break;
                }    
            }
        }
        
        $this->book->save();
    }

  }