如何获取帖子评论数以显示在后端帖子列表中？

BlogPost:
  actAs:
    Timestampable: ~
    I18n:
      fields: [title, body]
  tableName: blog_posts
  columns:
    #id: { type: integer(4), primary: true, autoincrement: true }
    user_id: { type: integer }
    title: { type: string(255) }
    body: { type: text }
  relations:
    User:
      type: one
      class: sfGuardUser
      local: user_id
      foreign: id
    Comments:
      type: many
      class: BlogComment
      local: id
      foreign: post_id

BlogComment:
  actAs:
    Timestampable: ~
  tableName: blog_comments
  columns:
    #id: { type: integer(4), primary: true, autoincrement: true }
    post_id: { type: integer }
    user_id: { type: integer }
    body: { type: text }
  relations:
    Post:
      type: one
      class: BlogPost
      local: post_id
      foreign: id

class BlogPostQuery extends Doctrine_Query {

        /**
         *
         * @param Doctrine_Connection $conn
         * @param string $class
         * @return BlogPostQuery
         */
        public static function create($conn = null, $class = null) {
            return parent::create($conn, \'BlogPostQuery\')
                    ->from(\'BlogPost p\');
        }

        /**
         *
         * @param string $fields
         * @return BlogPostQuery
         */
        public function addSelf($fields = \'p.*\') {
            return $this
            ->addSelect($fields);
        }

        /**
         *
         * @param string $fields
         * @return BlogPostQuery
         */
        public function addUsers($fields = \'u.*\') {
            return $this
            ->addSelect($fields)
            ->innerJoin(\'p.User u\')
            ->addGroupBy(\'u.id\');
        }

        /**
         *
         * @param string $fields
         * @return BlogPostQuery
         */
        public function addComments($fields = \'pc.*\') {
            return $this
            ->addSelect($fields)
            ->leftJoin(\'p.Comments pc\')
            ->addGroupBy(\'p.id\');
        }


        public function addCommentsCount($alias = \'nb_comments\') {
            return $this
            ->addSelect(sprintf(\'COUNT(pc.id) as %s\', $alias))
            ->addGroupBy(\'p.id\');
        }
     }

class BlogPostTable extends Doctrine_Table
{
    /**
     * Returns an instance of this class.
     *
     * @return object BlogPostTable
     */
    public static function getInstance()
    {
        return Doctrine_Core::getTable(\'BlogPost\');
    }

    public static function findAllWithCountComments() {   
        return BlogPostQuery::create()
                ->addSelf()
                ->addUsers()
                ->addComments()
                ->addCommentsCount()
                ->execute();
    }

}

list:
        title: Blog Posts Managment
        display: [id,title,User,nb_comments]
        table_method: findAllWithCountComments