Question

我在firebase实时数据库机智字段中有一个用户表：

userKey
  - uid
  - emailVerfied
  - attempts

我想观察userKey/attempts字段中的更改，我有以下触发设置：

 export const onUpdate = functions.database
.ref('/users/{uid}/attempts').onUpdate( event => {

    const record = event.after.val();

    // sending an email to myself, 
    adminLog(
          `user ${record.email} requested a new confirmation email`
        , `delivered from realtime.onUpdate with user ${record.uid}`);

})

每次更新字段attempt时都会触发此功能，但显然无法按照我的意图检索record.uid，因为发送的电子邮件如下所示：

delivered from realtime.onUpdate with user undefined

检索数据库值的快照的正确方法是什么？

Answer 1

使用您当前的代码和数据结构，uid中'/users/{uid}/attempts'的值实际上为userKey，而不是uid的值userKey {1}}。

要在云功能代码中获取此值，您应该

 event.params.uid

因为您使用的Firebase SDK for Cloud Functions版本是＆lt; 1.0.0（见下文）

如果相反，您希望获得uid的值而不是userKey的值，则应该在上一级听取，如下所示：

export const onUpdate = functions.database.ref('/users/{userKey}').onUpdate(...)   //I just changed, for clarity, to userKey, instead of uid

我建议您将代码升级到v1.0.0（请参阅文档here），然后执行以下操作：

 functions.database.ref('/users/{userKey}').onUpdate((change, context) => {
  const beforeData = change.before.val(); // data before the update
  const afterData = change.after.val(); // data after the update

  //You can then check if beforeData.attempts and afterData.attempts are different and act accordingly

  //You get the value of uid with: afterData.uid

  //You get the value of userKey (from the path) with: context.params.userKey

});

Firebase实时数据库和云功能：观察用户的子项在尝试事件值时返回undefined

1 个答案: