我在初始化Firebase时遇到了问题和项目，而我刚刚更新我的firebase-tools和firebase到版本9现代web模块化风格一个星期以来，没有任何东西对flutter的文档有帮助，它仍然是版本8，这是老式的compat类型，当我跟踪firebase文档时，它更新了flutter的抛出错误。我需要你的帮助，请提供一些解决方案。
core.dart:56 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'app')
at Object.app$ [as app] (core.dart:56)
at initializeApp (firebase_core_web.dart:68)
at initializeApp.next (<anonymous>)
at runBody (async_patch.dart:84)
at Object._async [as async] (async_patch.dart:123)
at firebase_core_web.FirebaseCoreWeb.new.initializeApp (firebase_core_web.dart:28)
at initializeApp (firebase.dart:42)
at initializeApp.next (<anonymous>)
at runBody (async_patch.dart:84)
at Object._async [as async] (async_patch.dart:123)
at Function.initializeApp (firebase.dart:38)
at main$ (main.dart:9)
at main$.next (<anonymous>)
at runBody (async_patch.dart:84)
at Object._async [as async] (async_patch.dart:123)
at main$ (main.dart:7)
at main (web_entrypoint.dart:19)
at main.next (<anonymous>)
at async_patch.dart:45
at _RootZone.runUnary (zone.dart:1613)
at _FutureListener.thenAwait.handleValue (future_impl.dart:155)
at handleValueCallback (future_impl.dart:707)
at Function._propagateToListeners (future_impl.dart:736)
at _Future.new.[_completeWithValue] (future_impl.dart:542)
at future.dart:401
at _RootZone.runUnary (zone.dart:1613)
at _FutureListener.then.handleValue (future_impl.dart:155)
at handleValueCallback (future_impl.dart:707)
at Function._propagateToListeners (future_impl.dart:736)
at _Future.new.[_completeWithValue] (future_impl.dart:542)
at async._AsyncCallbackEntry.new.callback (future_impl.dart:580)
at Object._microtaskLoop (schedule_microtask.dart:40)
at _startMicrotaskLoop (schedule_microtask.dart:49)
at async_patch.dart:166
和
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
js_primitives.dart:30 The following JSNoSuchMethodError was thrown building MyApp(dirty):
js_primitives.dart:30 TypeError: Cannot read properties of undefined (reading 'app')
js_primitives.dart:30
js_primitives.dart:30 The relevant error-causing widget was:
js_primitives.dart:30 MyApp file:///C:/Users/Neha/AndroidStudioProjects/devcom/lib/main.dart:10:10
js_primitives.dart:30
js_primitives.dart:30 When the exception was thrown, this was the stack:
js_primitives.dart:30 C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 236:49 throw_
js_primitives.dart:30 packages/firebase_core_web/firebase_core_web.dart 73:3 _catchJSError
js_primitives.dart:30 packages/firebase_core_web/src/firebase_core_web.dart 138:13 app
js_primitives.dart:30 packages/firebase_core/src/firebase.dart 55:41 app
js_primitives.dart:30 packages/firebase_auth/src/firebase_auth.dart 38:47 get instance
js_primitives.dart:30 packages/devcom/auth.dart 12:51 new
js_primitives.dart:30 packages/devcom/main.dart 17:13 build
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 4648:28 build
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 4574:15 performRebuild
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 4267:5 rebuild
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 4553:5 [_firstBuild]
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 4548:5 mount
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 3611:13 inflateWidget
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 3363:18 updateChild
js_primitives.dart:30 packages/flutter/src/widgets/binding.dart 1189:16 [_rebuild]
js_primitives.dart:30 packages/flutter/src/widgets/binding.dart 1159:5 mount
js_primitives.dart:30 packages/flutter/src/widgets/binding.dart 1104:16 <fn>
js_primitives.dart:30 packages/flutter/src/widgets/framework.dart 2535:19 buildScope
js_primitives.dart:30 packages/flutter/src/widgets/binding.dart 1103:12 attachToRenderTree
js_primitives.dart:30 packages/flutter/src/widgets/binding.dart 936:24 attachRootWidget
js_primitives.dart:30 packages/flutter/src/widgets/binding.dart 917:7 <fn>
js_primitives.dart:30 C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/isolate_helper.dart 48:19 internalCallback
js_primitives.dart:30
js_primitives.dart:30 ════════════════════════════════════════════════════════════════════════════════════════════════════
main.dart:
import 'package:flutter/material.dart';
import 'package:devcom/auth.dart';
import 'package:devcom/auth_provider.dart';
import 'package:devcom/root_page.dart';
import 'package:firebase_core/firebase_core.dart';
void main() async {
WidgetsFlutterBinding.ensureInitialized();
Firebase.initializeApp();
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return AuthProvider(
auth: Auth(),
child: MaterialApp(
title: 'Flutter login demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: RootPage(),
),
);
}
}
index.html:
<!DOCTYPE html>
<html>
<head>
<!-- <script src="https://www.gstatic.com/firebasejs/9.0.1/firebase-app.js" type = "module"></script>
<script src="https://www.gstatic.com/firebasejs/9.0.1/firebase-analytics.js" type = "module"> </script>
<script src="https://www.gstatic.com/firebasejs/9.0.1/firebase-auth.js" type = "module"></script> -->
<meta charset="UTF-8">
<meta content="IE=Edge" http-equiv="X-UA-Compatible">
<meta name="description" content="A new Flutter project.">
<!-- iOS meta tags & icons -->
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<meta name="apple-mobile-web-app-title" content="devcom">
<link rel="apple-touch-icon" href="icons/Icon-192.png">
<!-- Favicon -->
<link rel="shortcut icon" type="image/png" href="favicon.png" />
<title>Devcom</title>
<link rel="manifest" href="manifest.json">
</head>
<body >
<!-- The core Firebase JS SDK is always required and must be listed first -->
<script type="module">
import { initializeApp } from 'https://www.gstatic.com/firebasejs/9.0.1/firebase-app.js';
import { } from 'https://www.gstatic.com/firebasejs/9.0.1/firebase-auth.js';
import { getAnalytics } from "https://www.gstatic.com/firebasejs/9.0.1/firebase-analytics.js";
const firebaseConfig = {
apiKey: "...",
authDomain: "......",
databaseURL: ".....",
projectId: "...",
storageBucket: "",
messagingSenderId: "",
measurementId: "",
appId: "1:.........:web:...........",
};
const app = initializeApp({ firebaseConfig });
// const app = getAnalytics({ firebaseConfig })
</script>
<script>
var serviceWorkerVersion = null;
var scriptLoaded = false;
function loadMainDartJs() {
if (scriptLoaded) {
return;
}
scriptLoaded = true;
var scriptTag = document.createElement('script');
scriptTag.src = 'main.dart.js';
scriptTag.type = 'application/javascript';
document.body.append(scriptTag);
}
if ('serviceWorker' in navigator) {
// Service workers are supported. Use them.
window.addEventListener('load', function () {
// Wait for registration to finish before dropping the <script> tag.
// Otherwise, the browser will load the script multiple times,
// potentially different versions.
var serviceWorkerUrl = 'flutter_service_worker.js?v=' + serviceWorkerVersion;
navigator.serviceWorker.register(serviceWorkerUrl)
.then((reg) => {
function waitForActivation(serviceWorker) {
serviceWorker.addEventListener('statechange', () => {
if (serviceWorker.state == 'activated') {
console.log('Installed new service worker.');
loadMainDartJs();
}
});
}
if (!reg.active && (reg.installing || reg.waiting)) {
// No active web worker and we have installed or are installing
// one for the first time. Simply wait for it to activate.
waitForActivation(reg.installing ?? reg.waiting);
} else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
// When the app updates the serviceWorkerVersion changes, so we
// need to ask the service worker to update.
console.log('New service worker available.');
reg.update();
waitForActivation(reg.installing);
} else {
// Existing service worker is still good.
console.log('Loading app from service worker.');
loadMainDartJs();
}
});
// If service worker doesn't succeed in a reasonable amount of time,
// fallback to plaint <script> tag.
setTimeout(() => {
if (!scriptLoaded) {
console.warn(
'Failed to load app from service worker. Falling back to plain <script> tag.',
);
loadMainDartJs();
}
}, 4000);
});
} else {
// Service workers not supported. Just drop the <script> tag.
loadMainDartJs();
}
</script>
</body>
</html>您的flutter代码没有遵循文档的建议，特别是在哪里以及如何调用Firebase.initializeApp();。
下面是直接来自文档的一个片段:
import 'package:flutter/material.dart';
// Import the firebase_core plugin
import 'package:firebase_core/firebase_core.dart';
void main() {
WidgetsFlutterBinding.ensureInitialized();
runApp(App());
}
/// We are using a StatefulWidget such that we only create the [Future] once,
/// no matter how many times our widget rebuild.
/// If we used a [StatelessWidget], in the event where [App] is rebuilt, that
/// would re-initialize FlutterFire and make our application re-enter loading state,
/// which is undesired.
class App extends StatefulWidget {
// Create the initialization Future outside of `build`:
@override
_AppState createState() => _AppState();
}
class _AppState extends State<App> {
/// The future is part of the state of our widget. We should not call `initializeApp`
/// directly inside [build].
final Future<FirebaseApp> _initialization = Firebase.initializeApp();
@override
Widget build(BuildContext context) {
return FutureBuilder(
// Initialize FlutterFire:
future: _initialization,
builder: (context, snapshot) {
// Check for errors
if (snapshot.hasError) {
return SomethingWentWrong();
}
// Once complete, show your application
if (snapshot.connectionState == ConnectionState.done) {
return MyAwesomeApp();
}
// Otherwise, show something whilst waiting for initialization to complete
return Loading();
},
);
}
}
runApp(App());之后，该函数被调用。Firebase.initializeApp();不仅返回Future<FirebaseApp>(在代码中没有返回await)，而且它是主小部件状态的一部分。
Firebase的Flutter Web绑定是建立在v9之前的API之上的。据我所知，在Github的仓库中，还没有关于将它们移植到v9的讨论。我建议让库的作者决定何时迁移到v9模块化API风格的最佳时机，并在此之前使用v8，如FlutterFire文档中所示，将Firebase sdk添加到您的web应用程序。
如果您坚持要迁移到v9，您可以使用它的-compat版本，它将以前的API样式固定在新的模块化版本上。这将允许您使用最新的构建，尽管它不会给您提供新的模块化API的(全部)大小优势。