我在使用信息流评论中给出的安全规则，就报错了？

{
  "read": true,
  "create": "doc.commenter == auth.openid",
  "update": "doc.commenter == auth.openid || get('database.user.${auth.openid}').isManager",
  "delete": "doc.commenter == auth.openid || get('database.user.${auth.openid}').isManager",
}

无论怎么修改都是：Error: InvalidParameter, rule invalid