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node.js - Firestore 数据库未与 Firebase 云功能连接

问题描述

我正在尝试通过 Firebase 云功能中使用的 Express.js 检索 Firestore 数据库信息。我在函数文件夹中的 index.js 文件如下所示：

const functions = require('firebase-functions');
const admin = require("firebase-admin");
const db = admin.firestore();
admin.initializeApp();
const express = require('express');
const app= express();

app.get("/teacher/:uid",function(req,res){
    const id = req.params.uid;
    const doc = db.collection('users').doc(id).get();
    res.send(doc);
    //res.render("teacher",{id : id});
})

我的 index.html 文件的脚本部分如下所示：

<body>

// some html code 
<!---script follow-->
<script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha384-J6qa4849blE2+poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ+n" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
<script src="https://www.gstatic.com/firebasejs/7.14.2/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.14.2/firebase-auth.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.14.2/firebase-firestore.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.14.2/firebase-functions.js"></script>
<script>
  // web app's Firebase configuration
  var firebaseConfig = {
    apiKey: "xyz",
    authDomain: "xyz",
    databaseURL: "xyz",
    projectId: "xyz",
    appId: "xyz"
  };
  // i have replaced the actual keys and urls with xyz

  firebase.initializeApp(firebaseConfig);
  const auth= firebase.auth();
  const db= firebase.firestore();
  const functions = firebase.functions();

</script>

<script src="auth.js"></script>
</body>

ERROR : 
on command firebase serve --only functions , i am getting this error 

 Error: The default Firebase app does not exist. Make sure you call initializeApp() before using any of the Firebase services.
    at FirebaseAppError.FirebaseError [as constructor] (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/utils/error.js:42:28)
    at FirebaseAppError.PrefixedFirebaseError [as constructor] (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/utils/error.js:88:28)
    at new FirebaseAppError (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/utils/error.js:123:28)
    at FirebaseNamespaceInternals.app (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/firebase-namespace.js:101:19)
    at FirebaseNamespace.app (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/firebase-namespace.js:452:30)
    at FirebaseNamespace.ensureApp (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/firebase-namespace.js:468:24)
    at Proxy.fn (/home/chahat/Desktop/firebase/functions/node_modules/firebase-admin/lib/firebase-namespace.js:327:30)
    at Object.<anonymous> (/home/chahat/Desktop/firebase/functions/index.js:3:18)
    at Module._compile (internal/modules/cjs/loader.js:1156:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1176:10)
⚠  We were unable to load your functions code. (see above)

标签： node.jsfirebaseexpressgoogle-cloud-functionsbackend

解决方案

您应该在 Cloud Function 代码中更改几个部分：

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

 const db = admin.firestore();   //#1

 const express = require('express');
 const app= express();

 app.get("/teacher/:uid",function(req, res){
    const id = req.params.uid;
    db.collection('users').doc(id).get()   //#2  
    .then(snap => {
        res.send(snap.data());
    })
    .catch(error => {...})
 })
  1. 在初始化 Admin SDKadmin.firestore() 之后定义 Firestore 。
  2. 该get()方法是异步的。您需要等待 Promise 的返回解决，然后才能返回响应。文档中的更多详细信息：https ://firebase.google.com/docs/firestore/query-data/get-data#g​​et_a_document和https://firebase.google.com/docs/functions/video-series

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