node.js - Firebase 函数 : cannot read property 'user_id' of undefined

Question

我正在尝试使用我的移动应用程序执行一个简单的 hello world firebase 功能，我想记录用户 ID，以便我可以看到该功能是否有效。这是我当前的 JavaScript 代码:

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;
});

当新数据写入特定数据库表时会触发，但会出现此错误:

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:

Answer 1

您需要安装最新的 firebase-functions 和 firebase-admin:

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

为了能够使用新的 API，请在此处查看更多信息:

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

改变这个:

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);

进入这个:

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);

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

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:

Cloud functions v1.0 Changes

EventContext#params

Change