Setup Project
在 Google firebase console 上创建项目 try-serverless-firebase，或者使用 Firebase CLI 工具在客户端创建项目。
跟随 Firebase 文档 https://firebase.google.com/docs/functions/get-started 练习以下操作。Firebase CLI 是管理、查看和部署 Firebase 项目的客户端命令行工具，安装 Firebase CLI ：
npm install -g firebase-tools
登录 firebase 账号，firebase 使用 Ouath2 授权方式登录 Google 账号
firebase login
创建项目并初始化 Google Cloud functions 功能，根据提醒选择 Project setup, JavaScript/TypeScript, ESLint, Install Dependencies 。
$ mkdir try-serverless-firebase
$ cd try-serverless-firebase
$ firebase init functions
生成的项目目录结构如下
try-serverless-firebase
+- .firebaserc # Hidden file that helps you quickly switch between
| # projects with `firebase use`
|
+- firebase.json # Describes properties for your project
|
+- functions/ # Directory containing all your functions code
|
+- .eslintrc.json # Optional file containing rules for JavaScript linting.
|
+- package.json # npm package file describing your Cloud Functions code
|
+- index.js # main source file for your Cloud Functions code
|
+- node_modules/ # directory where your dependencies (declared in
# package.json) are installed
如果在 firebase init 步骤中没有选择项目，那么可以使用 Firebase CLI 重新设置:
firebase list列出所有可用的项目，如果没有可以到 Firebase console 中新建firebase use <Project ID>指定当前目录要对应的项目
Hello world
在 ./functions/index.js 里编写程序如下：
const functions = require('firebase-functions');
// The Firebase Admin SDK to access the Firebase Realtime Database.
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);
// Take the text parameter passed to this HTTP endpoint and insert it into the
// Realtime Database under the path /messages/:pushId/original
exports.addMessage = functions.https.onRequest((req, res) => {
// Grab the text parameter.
const original = req.query.text;
// Push the new message into the Realtime Database using the Firebase Admin SDK.
admin.database().ref('/messages').push({original: original}).then(snapshot =>
// Redirect with 303 SEE OTHER to the URL of the pushed object in the Firebase console.
res.redirect(303, snapshot.ref)
).catch(err => {
if (err) console.log(err);
return res.send("ok");
});
});
部署此 Function 到 Firebase 上:
firebase deploy --only functions or firebase deploy --only functions:addMessage
在 Firebase console functions 栏里会出现这一条记录
| Function | Event | Executions | Median run time |
|---|---|---|---|
| addMessage | HTTP Request https://us-central1-try-serverless-firebase.cloudfunctions.net/addMessage | - | - |
在浏览器打开链接 https://us-central1-try-serverless-firebase.cloudfunctions.net/addMessage?text=Hello world! 它会跳转到 Firebase Realtime Database 里此条 Message 页面，因为我们在程序里指定了这样的返回：
res.redirect(303, snapshot.ref);
Event-driven Functions
Serverless 架构实现的核心概念就是事件驱动的函数. 想要实现自己的逻辑, 只需要编写当某个事件发生时所要执行的函数即可. 例如接下来我们要实现把保存的text转换成大写字母, 可以编写一个 on write original 事件所要执行的函数:
// Listens for new messages added to /messages/:pushId/original and creates an
// uppercase version of the message to /messages/:pushId/uppercase
// [START makeUppercaseTrigger]
exports.makeUppercase = functions.database.ref('/messages/{pushId}/original')
.onWrite(event => {
// [END makeUppercaseTrigger]
// [START makeUppercaseBody]
// Grab the current value of what was written to the Realtime Database.
const original = event.data.val();
console.log('Uppercasing', event.params.pushId, original);
const uppercase = original.toUpperCase();
// You must return a Promise when performing asynchronous tasks inside a Functions such as
// writing to the Firebase Realtime Database.
// Setting an "uppercase" sibling in the Realtime Database returns a Promise.
return event.data.ref.parent.child('uppercase').set(uppercase);
// [END makeUppercaseBody]
});
使用Firebase封装好的函数来为数据库的某个消息字段保存时指定函数逻辑:
functions.database.ref('/messages/{pushId}/original').onWrite(event => { ... });
重新部署之后, 再次调用addMessage url 可以看到消息如下:
-KtttKs7lWKs_CgO2PqK
|--- original: "Hello world!"
|--- uppercase: "HELLO WORLD!"
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