如何解决这个 firebase is not defined 错误？

Question

I'm new to firebase/javascript/html coding, so I really don't know what I'm doing. But I was following a tutorial on how to make firebase work with a WebGL Unity build and got stuck here:

html code `

<script type="module">
          // Import the functions you need from the SDKs you need
          import { initializeApp } from "https://www.gstatic.com/firebasejs/9.15.0/firebase-app.js";
          import { getDatabase } from "https://www.gstatic.com/firebasejs/9.15.0/firebase-database.js";
          // Your web app's Firebase configuration
          // For Firebase JS SDK v7.20.0 and later, measurementId is optional
          const firebaseConfig = {
              apiKey: "apikey",
              authDomain: "authDomain.firebaseapp.com",
              databaseURL: "databaseURL.firebasedatabase.app",
              projectId: "projectId",
              storageBucket: "storageBucket.appspot.com",
              messagingSenderId: "messagingSenderId",
              appId: "appId",
              measurementId: "G-measurementId"
          };
          // Initialize Firebase
          const app = initializeApp(firebaseConfig);
          const db = getDatabase(app);
      </script>

jslib script:

PostJSON: function(path, value, objectName, callback, fallback) {
        var parsedPath = Pointer_stringify(path);
        var parsedValue = Pointer_stringify(value);
        var parsedObjectName = Pointer_stringify(objectName);
        var parsedCallback = Pointer_stringify(callback);
        var parsedFallback = Pointer_stringify(fallback);

        try {

            firebase.database().ref(parsedPath).set(JSON.parse(parsedValue)).then(function(unused) {
                unityInstance.Module.SendMessage(parsedObjectName, parsedCallback, "Success: " + parsedValue + " was posted to " + parsedPath);
            });

        } catch (error) {
            unityInstance.Module.SendMessage(parsedObjectName, parsedFallback, JSON.stringify(error, Object.getOwnPropertyNames(error)));
        }
    }

`

Every time I try to post a value it says: firebase is not defined. What am I doing wrong?

Answer 1

You're mixing the namespaced firebase.database() syntax of Firebase SDK versions 8 and before with the modular initializeApp syntax of Firebase SDK versions 9 and later, which doesn't work.

Since you're initializing the modular SDK, your database access code should use the new modular syntax too:

import { getDatabase, ref, set } from "firebase/database";

const db = getDatabase();
set(ref(db, parsedPath), JSON.parse(parsedValue)).then(function(unused) {
    unityInstance.Module.SendMessage(parsedObjectName, parsedCallback, "Success: " + parsedValue + " was posted to " + parsedPath);
});

To learn how to upgrade the code, have a look at the migration guide and keep the Firebase documentation handy as all code samples in there have variants for both syntaxes such as in this page on reading and writing data .