如何从 Firebase 虚拟主机读取 Firebase 数据库？答案

【问题标题】：How to read Firebase Database from Firebase Web Hosting?如何从 Firebase 虚拟主机读取 Firebase 数据库？
【发布时间】：2020-12-25 19:22:29
【问题描述】：

我是 Firebase 托管的新手，我想从网络读取数据。我在 Firebase 中的数据库如下所示：

{
  "contactos" : {
    "-MGcSVviK2nxd52KNtZ" : {
      "email" : "david@hotmail.com",
      "fecha" : 1599480318009,
      "nombre" : "David R",
    },
    "-RTcnLta8ud8Dw168oLS" : {
      "email" : "roger@hotmail.com",
      "fecha" : 1599486127716,
      "nombre" : "Roger H",
    }
  }
}

我安装了 Firebase 工具并初始化了项目，该项目创建了一个 index.html 文件，警告我配置成功...

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Welcome to Firebase Hosting</title>

    <!-- update the version number as needed -->
    <script defer src="/__/firebase/8.2.1/firebase-app.js"></script>
    <!-- include only the Firebase features as you need -->
    <script defer src="/__/firebase/8.2.1/firebase-auth.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-database.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-firestore.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-functions.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-messaging.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-storage.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-analytics.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-remote-config.js"></script>
    <script defer src="/__/firebase/8.2.1/firebase-performance.js"></script>
    <!-- 
      initialize the SDK after all desired features are loaded, set useEmulator to false
      to avoid connecting the SDK to running emulators.
    -->
    <script defer src="/__/firebase/init.js?useEmulator=true"></script>

    <style media="screen">
      body { background: #ECEFF1; color: rgba(0,0,0,0.87); font-family: Roboto, Helvetica, Arial, sans-serif; margin: 0; padding: 0; }
      #message { background: white; max-width: 360px; margin: 100px auto 16px; padding: 32px 24px; border-radius: 3px; }
      #message h2 { color: #ffa100; font-weight: bold; font-size: 16px; margin: 0 0 8px; }
      #message h1 { font-size: 22px; font-weight: 300; color: rgba(0,0,0,0.6); margin: 0 0 16px;}
      #message p { line-height: 140%; margin: 16px 0 24px; font-size: 14px; }
      #message a { display: block; text-align: center; background: #039be5; text-transform: uppercase; text-decoration: none; color: white; padding: 16px; border-radius: 4px; }
      #message, #message a { box-shadow: 0 1px 3px rgba(0,0,0,0.12), 0 1px 2px rgba(0,0,0,0.24); }
      #load { color: rgba(0,0,0,0.4); text-align: center; font-size: 13px; }
      @media (max-width: 600px) {
        body, #message { margin-top: 0; background: white; box-shadow: none; }
        body { border-top: 16px solid #ffa100; }
      }
    </style>
  </head>
  <body>
    <div id="message">
      <h2>Welcome</h2>
      <h1>Firebase Hosting Setup Complete</h1>
      <p>You're seeing this because you've successfully setup Firebase Hosting. Now it's time to go build something extraordinary!</p>
      <a target="_blank" href="https://firebase.google.com/docs/hosting/">Open Hosting Documentation</a>
    </div>
    <p id="load">Firebase SDK Loading&hellip;</p>

    <script>
      document.addEventListener('DOMContentLoaded', function() {
        const loadEl = document.querySelector('#load');
        // // ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
        // // The Firebase SDK is initialized and available here!
        //
        // firebase.auth().onAuthStateChanged(user => { });
        // firebase.database().ref('/path/to/ref').on('value', snapshot => { });
        // firebase.firestore().doc('/foo/bar').get().then(() => { });
        // firebase.functions().httpsCallable('yourFunction')().then(() => { });
        // firebase.messaging().requestPermission().then(() => { });
        // firebase.storage().ref('/path/to/ref').getDownloadURL().then(() => { });
        // firebase.analytics(); // call to activate
        // firebase.analytics().logEvent('tutorial_completed');
        // firebase.performance(); // call to activate
        //
        // // ????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

        try {
          let app = firebase.app();
          let features = [
            'auth', 
            'database', 
            'firestore',
            'functions',
            'messaging', 
            'storage', 
            'analytics', 
            'remoteConfig',
            'performance',
          ].filter(feature => typeof app[feature] === 'function');
          loadEl.textContent = `Firebase SDK loaded with ${features.join(', ')}`;
        } catch (e) {
          console.error(e);
          loadEl.textContent = 'Error loading the Firebase SDK, check the console.';
        }
      });
    </script>
  </body>
</html>

我想做的是在一个 url 类型中

https://defaultname.web.app/-MGcSVviK2nxd52KNtZ 或

https://defaultname.web.app/contactos?id=-MGcSVviK2nxd52KNtZ

任何人都可以读取链接到该对象的基本数据，在这种情况下：

电子邮件 david@hotmail.com

日期 1599480318009

姓名大卫·R

我的基本问题是：我需要使用 Java Script 吗？ 如何编写文件在Firebase中读取并在html中显示？如何使用url中的参数？

【问题讨论】：

标签： html firebase-realtime-database firebase-hosting

【解决方案1】：

是的，您需要执行 Javascript 来为您的应用程序设置路由才能做到这一点

您可以创建一个路由器来为您处理。

深入了解以下内容：

const ContactosComponent = {
  render: async() => {
    // imagine location.pathname being equal to /contactos/<id>
    const contactoId = location.pathname.split('/').pop()
    // retrieve contacto info
    const contacto = (await firebase.firestore().collection('contactos').doc(contactoId).get()).data()

    return `<span> Hello ${contacto.nombre}</span>`
  }
}

// here you declare the routes of your application
const routes = [
  {
    path: '/contactos',
    component: ContactosComponent
  }
]

// a function to find the specific route that your user requests
const findComponentByPath = (path) => routes.find(r => r.path.match(new RegExp(`^\\${path}$`, 'gm')))

const redirectTo = async (path) => {
  console.log('path', path)
  const { component /* = ErrorComponent */ } = findComponentByPath(path) || {}
  console.log('component', component)
  // ATTENTION: you need to have a div with this id into your html
  document.getElementById('app').innerHTML = await component.render()
}

const router = () => {
  const path = location.pathname
  redirectTo(path)
}

然后您将跟踪您的路由更改并将它们发送到路由器，如下所示：

document.addEventListener('DOMContentLoaded', function() {
  window.addEventListener('hashchange', router)
  window.addEventListener('load', router)
  ...

欲了解更多信息，请深入阅读this tutorial

如果您对此帖子有任何疑问，请发表评论

【讨论】：

@malarahfelipe 听起来很棒！！我真的很抱歉，但我不知道如何实施它。我在 VS Code 中创建了一个名为 main.js 的新文件，其中包含您分享给我的代码，并且我从 index.html 中做了一个引用......类似于<script src="js/main.js"></script>。当我执行 firebase deploy 时，我看不到任何更改，您能否给我一个分步指南
@malarahfelipe 你能指出前面的步骤吗？我认为您的代码将在 JS 服务器中实现。我需要什么来实现它？我刚刚发布了一个 index.html，我尝试实现一个像您的教程一样的服务器，但它不起作用。你能具体说明我需要什么来测试你的 JS 代码吗？
嘿大卫，抱歉我没有看到你 25 日的最后一条消息，现在将尝试在以下 cmets 上进行解释
当你通过script标签加载文件时，你能看到console.log有什么东西吗？值得一提的是，您必须在所有库导入（firebase 或任何其他）之后加载此脚本标签
如果您愿意，我们可以将此对话移至聊天室