Firebase函数:无法读取未定义的属性"user_id" [英] Firebase functions: cannot read property 'user_id' of undefined

问题描述

我正在尝试用我的移动应用程序做一个简单的hello world firebase函数，我想记录用户ID，以便可以看到该函数确实起作用. 这是我当前的javascript代码:

I am trying to do a simple hello world firebase function with my mobile app, I want to log the user ID so I can see that the function does work. This is my current javascript code:

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

exports.sendNotification = functions.database.ref('/notifications/{user_id}').onWrite((event) => {

  console.log('Testing stuff', event.params.user_id);

  return;
});

在将新数据写入特定的数据库表时会触发，但会显示此错误:

It does trigger when new data is written to specific databasetable but this error shows up:

TypeError: Cannot read property 'user_id' of undefined
    at exports.sendNotification.functions.database.ref.onWrite (/user_code/index.js:8:44)
    at Object.<anonymous> (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:112:27)
    at next (native)
    at /user_code/node_modules/firebase-functions/lib/cloud-functions.js:28:71
    at __awaiter (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:24:12)
    at cloudFunction (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:82:36)
    at /var/tmp/worker/worker.js:700:26
    at process._tickDomainCallback (internal/process/next_tick.js:135:7)

通知数据库如下所示:

The notification database looks like this:

推荐答案

您需要安装最新的firebase功能和firebase-admin:

npm install firebase-functions@latest firebase-admin@latest --save
npm install -g firebase-tools

要能够使用新的API，请在此处查看更多信息:

to be able to use the new API, check here for more info:

https://firebase.google.com/docs/functions/get-开始#set_up_and_initialize

更改此内容:

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

exports.sendNotification = functions.database.ref('/notifications/{user_id}').onWrite((event) => {

console.log('Testing stuff', event.params.user_id);

为此:

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

exports.sendNotification = functions.database.ref('/notifications/{user_id}').onWrite((change, context) => {

console.log('Testing stuff', context.params.user_id);

对于onWrite和onUpdate事件，数据参数具有before和after字段.每个都是DataSnapshot，具有与 admin中可用的相同方法.database.DataSnapshot

For onWrite and onUpdate events, the data parameter has before and after fields. Each of these is a DataSnapshot with the same methods available in admin.database.DataSnapshot

---

params

一个对象，该对象在提供给Realtime数据库触发器的ref()方法的path参数中包含通配符的值.

An object containing the values of the wildcards in the path parameter provided to the ref() method for a Realtime Database trigger.

更多信息在这里:

云函数v1.0更改

EventContext#params

更改

这篇关于Firebase函数:无法读取未定义的属性"user_id"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！