如何使用Cloud Functions for Firebase更新Firebase实时数据库中的值 [英] how to update a value in firebase realtime database using Cloud Functions for Firebase

问题描述

我通过firebase文档使用Cloud Functions for Firebase更新实时数据库中的值，但无法理解.

I went though the firebase docs for updating a value in realtime database using Cloud Functions for Firebase, but am not able to understand.

我的数据库结构是

{   
 "user" : {
    "-KdD1f0ecmVXHZ3H3abZ" : {
      "email" : "[e-mail]",
      "first_name" : "John",
      "last_name" : "Smith",
      "isVerified" : false
    },
    "-KdG4iHEYjInv7ljBhgG" : {
      "email" : "[e-mail]",
      "first_name" : "Max1",
      "last_name" : "Rosse13131313l",
      "isVerified" : false
    },
    "-KdGAZ8Ws6weXWo0essF" : {
      "email" : "[e-mail]",
      "first_name" : "Max1",
      "last_name" : "Rosse13131313l",
      "isVerified" : false
    } 
}

我想使用数据库触发器云功能更新isVerified.我不知道如何使用云功能(语言:Node.JS)更新数据库值

I want to update the isVerified using database trigger cloud functions. I don't know how to update a database value using cloud functions (language : Node.JS)

当使用数据库触发器onWrite创建用户时，我编写了一个代码来自动更新用户键"isVerified"的值.我的代码是

I wrote a code to automatically update the value of the key 'isVerified' of a user, when the user is created by using database trigger onWrite. My code is

const functions = require('firebase-functions');

const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

exports.userVerification = functions.database.ref('/users/{pushId}')
    .onWrite(event => {
    // Grab the current value of what was written to the Realtime Database.
    var eventSnapshot = event.data;

    if (event.data.previous.exists()) {
        return;
    }

    eventSnapshot.update({
        "isVerified": true
    });
});

但是当我部署代码并将用户添加到数据库时，云功能日志显示以下错误

but when i deploy the code, and add a user to the database, the cloud function log shows the below error

TypeError: eventSnapshot.child(...).update is not a function
    at exports.userVerification.functions.database.ref.onWrite.event (/user_code/index.js:10:36)
    at /user_code/node_modules/firebase-functions/lib/cloud-functions.js:35:20
    at process._tickDomainCallback (internal/process/next_tick.js:129:7)

推荐答案

您正试图在DeltaSnapshot对象上调用update().在这种类型的对象上没有这种方法.

You are trying to call update() on a DeltaSnapshot object. There is no such method on that type of object.

var eventSnapshot = event.data;
eventSnapshot.update({
    "isVerified": true
});

event.data是 DeltaSnapshot .如果要在此对象表示的更改位置更改数据.使用其ref属性获取参考对象的保持状态:

event.data is a DeltaSnapshot. If you want to change the data at the location of the change represented by this object. Use its ref property to get a hold of a Reference object:

var ref = event.data.ref;
ref.update({
    "isVerified": true
});

此外，如果您要在函数中读取或写入数据库，则应始终返回承诺，指示更改何时完成:

Also, if you are reading or writing the database in a function, you should always return a Promise that indicates when the change is complete:

return ref.update({
    "isVerified": true
});

我建议从评论中采纳弗兰克的建议，并研究现有的示例代码和文档以更好地了解Cloud Functions的工作原理.

I would recommend taking Frank's advice from the comments and study the existing sample code and documentation to better understand how Cloud Functions works.

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