async def favorite_add(ns={}):
    """
    添加用户收藏
    :param ns: 包含userid, productid, favorite_type等参数
    :return: 操作结果
    """
    ns_dic = {
        'id': uuid(),  # 生成32位ID
        'userid': ns.get('userid'),
        'productid': ns.get('productid'),
        'favorite_type': ns.get('favorite_type', '1'),  # 默认为商品收藏
        'tag': ns.get('tag')  # 标签
    }
    
    # 处理userid
    if ns.get('userid'):
        ns_dic['userid'] = ns.get('userid')
    else:
        ns_dic['userid'] = await get_user()

    if not ns_dic.get('userid'):
        server_error(401)
        
    db = DBPools()
    async with db.sqlorContext('kboss') as sor:
        try:
            # 检查是否已收藏 处理tag是NULL的情况
            conditions = [
                "userid = '%s'" % ns_dic['userid'],
                "productid = '%s'" % ns_dic['productid'],
                "favorite_type = '%s'" % ns_dic['favorite_type'] if ns_dic['favorite_type'] is not None else "favorite_type IS NULL",
                "del_flg = '0'",
                "tag = '%s'" % ns_dic['tag'] if ns_dic['tag'] is not None else "tag IS NULL"
            ]
            check_sql = "SELECT id FROM user_favorite WHERE " + " AND ".join(conditions)
            
            check_result = await sor.sqlExe(check_sql, {})
            
            if check_result:
                return {
                    'status': False,
                    'msg': '已收藏关注'
                }
            
            # 执行收藏操作
            await sor.C('user_favorite', ns_dic)
            return {
                'status': True,
                'msg': '关注收藏成功'
            }
        except Exception as e:
            await sor.rollback()
            return {
                'status': False,
                'msg': '关注收藏失败, %s' % str(e)
            }

ret = await favorite_add(params_kw)
return ret