没有创建 Firebase App '[DEFAULT]' - 在 Flutter 和 Firebase 调用 Firebase.initializeApp()

Question

我正在构建一个 Flutter 应用程序并且我已经集成了 Firebase，但是当我点击一个按钮进行注册、登录或注销时，我总是收到这个错误。 我见过其他人问过同样的问题，但似乎没有一个对我有用。 我正在使用 Flutter 和Android Studio 。 我该如何解决这个问题？

这是我的代码的摘录

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.red,
      body: Center(
        child: Container(
          child: RaisedButton(
            onPressed: () {
              FirebaseAuth.instance.signOut().then((value) {
                Navigator.pushReplacement(
                    context,
                    MaterialPageRoute(
                        builder: (context) =>
                            LoginScreen()));
              });
            },
            child: Text("Logout"),
          )
        )
      )
    );
  }
}

下面是抛出的异常

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

When the exception was thrown, this was the stack:

#0      MethodChannelFirebase.app (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:118:5)
#1      Firebase.app (package:firebase_core/src/firebase.dart:52:41)
#2      FirebaseAuth.instance (package:firebase_auth/src/firebase_auth.dart:37:47)
#3      _HomeScreenState.build.<anonymous closure> (package:cosytok/screens/home.dart:20:28)
#4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:992:19)
#5      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1098:38)
#6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
#7      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
#8      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
#9      BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
#10     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
#11     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
#12     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
#13     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
#14     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
#15     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
#16     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
#17     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
#18     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
#19     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
#20     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
#24     _invoke1 (dart:ui/hooks.dart:267:10)
#25     _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
(elided 3 frames from dart:async)

Handler: "onTap"
Recognizer:
  TapGestureRecognizer#f0104
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

Answer 1

自 2020 年 8 月 17 日起

所有 Firebase 版本都已更新，现在您必须在使用任何 Firebase 产品之前调用Firebase.initializeApp() ，例如：

首先，所有 Firebase 产品现在都依赖于firebase_core版本（0.5.0+），因此您需要将其添加到pubspec.yaml文件中：

dependencies:
  flutter:
    sdk: flutter
  firebase_core : ^0.5.0
  # cloud_firestore: ^0.14.0 other firebase dependencies

然后你必须调用Firebase.initializeApp() ：

第一个例子

import 'package:flutter/material.dart';

// Import the firebase_core plugin
import 'package:firebase_core/firebase_core.dart';

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      // Initialize FlutterFire
      future: Firebase.initializeApp(),
      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();
      },
    );
  }
}

Firestore 的第二个示例：

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: FirstRoute(title: 'First Route'),
    );
  }
}

class FirstRoute extends StatefulWidget {
  FirstRoute({Key key, this.title}) : super(key: key);
  final String title;

  @override
  _FirstRouteState createState() => _FirstRouteState();
}

class _FirstRouteState extends State<FirstRoute> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("test"),
        ),
        body: FutureBuilder(
          future: getData(),
          builder: (context, AsyncSnapshot<DocumentSnapshot> snapshot) {
            if (snapshot.connectionState == ConnectionState.done) {
              return Column(
                children: [
                  Container(
                    height: 27,
                    child: Text(
                      "Name: ${snapshot.data.data()['name']}",
                      overflow: TextOverflow.fade,
                      style: TextStyle(fontSize: 20),
                    ),
                  ),
                ],
              );
            } else if (snapshot.connectionState == ConnectionState.none) {
              return Text("No data");
            }
            return CircularProgressIndicator();
          },
        ));
  }

  Future<DocumentSnapshot> getData() async {
    await Firebase.initializeApp();
    return await FirebaseFirestore.instance
        .collection("users")
        .doc("docID")
        .get();
  }
}

第三个例子：

在initState()中初始化它，然后调用setState() ，这将调用build()方法。

  @override
  void initState() {
    super.initState();
    Firebase.initializeApp().whenComplete(() { 
      print("completed");
      setState(() {});
    });
  }

第四个例子：

调用WidgetsFlutterBinding.ensureInitialized();后在main()方法中初始化；

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

注意：您只需调用initializeApp()一次

Answer 2

1. 添加到 pubspec.yaml

    firebase_core:

2. 添加到 main.dart

    import 'package:firebase_core/firebase_core.dart'; void main() async { WidgetsFlutterBinding.ensureInitialized(); await Firebase.initializeApp(); runApp(MyApp()); }

Answer 3

如果您按照Peter 的回答进行操作，但仍然遇到相同的错误，请检查以确保您的main function 中的任何其他内容都出现在await Firebase.initializeApp()调用之后，如下所示：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  FirebaseCrashlytics.instance.setCrashlyticsCollectionEnabled(true);
  FlutterError.onError = FirebaseCrashlytics.instance.recordFlutterError;
  runApp(MyApp());
}

Answer 4

自2017年8月起，Firebase服务全部更新，必须在main中调用Firebase.initializeApp()才能使用Firebase产品，例如：

如果你想在 flutter 应用程序中使用 firebase_core 插件，那么在你的 pubspec.yaml 文件中添加 firebase_core 如下

dependencies:
  flutter:
    sdk: flutter
  firebase_core: ^1.19.1

然后在您的应用中调用 Firebase.initializeApp():。 与以下内容相同：

import 'package:firebase_core/firebase_core.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

Answer 5

我正在构建一个 Flutter 应用程序，并且我已经集成了 Firebase，但是当我单击一个按钮进行注册、登录或注销时，我不断收到此错误。 我见过其他人问过同样的问题，但似乎没有一个对我有用。 我正在使用 Flutter 和Android Studio 。 我该如何解决这个问题？

这是我的代码的摘录

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.red,
      body: Center(
        child: Container(
          child: RaisedButton(
            onPressed: () {
              FirebaseAuth.instance.signOut().then((value) {
                Navigator.pushReplacement(
                    context,
                    MaterialPageRoute(
                        builder: (context) =>
                            LoginScreen()));
              });
            },
            child: Text("Logout"),
          )
        )
      )
    );
  }
}

下面是抛出的异常

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

When the exception was thrown, this was the stack:

#0      MethodChannelFirebase.app (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:118:5)
#1      Firebase.app (package:firebase_core/src/firebase.dart:52:41)
#2      FirebaseAuth.instance (package:firebase_auth/src/firebase_auth.dart:37:47)
#3      _HomeScreenState.build.<anonymous closure> (package:cosytok/screens/home.dart:20:28)
#4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:992:19)
#5      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1098:38)
#6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
#7      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
#8      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
#9      BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
#10     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
#11     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
#12     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
#13     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
#14     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
#15     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
#16     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
#17     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
#18     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
#19     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
#20     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
#24     _invoke1 (dart:ui/hooks.dart:267:10)
#25     _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
(elided 3 frames from dart:async)

Handler: "onTap"
Recognizer:
  TapGestureRecognizer#f0104
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

Answer 6

我正在构建一个 Flutter 应用程序，并且我已经集成了 Firebase，但是当我单击一个按钮进行注册、登录或注销时，我不断收到此错误。 我见过其他人问过同样的问题，但似乎没有一个对我有用。 我正在使用 Flutter 和Android Studio 。 我该如何解决这个问题？

这是我的代码的摘录

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.red,
      body: Center(
        child: Container(
          child: RaisedButton(
            onPressed: () {
              FirebaseAuth.instance.signOut().then((value) {
                Navigator.pushReplacement(
                    context,
                    MaterialPageRoute(
                        builder: (context) =>
                            LoginScreen()));
              });
            },
            child: Text("Logout"),
          )
        )
      )
    );
  }
}

下面是抛出的异常

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

When the exception was thrown, this was the stack:

#0      MethodChannelFirebase.app (package:firebase_core_platform_interface/src/method_channel/method_channel_firebase.dart:118:5)
#1      Firebase.app (package:firebase_core/src/firebase.dart:52:41)
#2      FirebaseAuth.instance (package:firebase_auth/src/firebase_auth.dart:37:47)
#3      _HomeScreenState.build.<anonymous closure> (package:cosytok/screens/home.dart:20:28)
#4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:992:19)
#5      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1098:38)
#6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:184:24)
#7      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:524:11)
#8      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:284:5)
#9      BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:219:7)
#10     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:477:9)
#11     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:78:12)
#12     PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:124:9)
#13     _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:377:8)
#14     PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:122:18)
#15     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:108:7)
#16     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:220:19)
#17     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:200:22)
#18     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:158:7)
#19     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:104:7)
#20     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:88:7)
#24     _invoke1 (dart:ui/hooks.dart:267:10)
#25     _dispatchPointerDataPacket (dart:ui/hooks.dart:176:5)
(elided 3 frames from dart:async)

Handler: "onTap"
Recognizer:
  TapGestureRecognizer#f0104
════════════════════════════════════════════════════════════════════════════════════════════════════

════════ Exception caught by gesture ═══════════════════════════════════════════════════════════════
The following FirebaseException was thrown while handling a gesture:
[core/no-app] No Firebase App '[DEFAULT]' has been created - call Firebase.initializeApp()

Answer 7

首先，添加这个依赖：

firebase_core :

第二：在项目主 function 中，添加这两行并使 function 异步：

void main() async {
    // These two lines
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();

    //
    runApp(MyApp());
}

现在你可以在项目中的任意文件或widget中正常使用Firebase了。

FutureBuilder小部件也可以工作，但您必须在每次要访问 Firebase 时添加它。

Answer 8

仅 Dart 初始化（推荐）

• 使用 CLI 在所有平台上初始化 Firebase。

• 无需添加任何本机代码。

• 无需下载任何 Google 服务文件。

1. 安装 FlutterFire CLI

    dart pub global activate flutterfire_cli

2. （可选）将以下行添加到您的~/.zshrc文件并保存

   export PATH="$PATH":"$HOME/.pub-cache/bin"

3. 运行configure ：

    flutterfire configure

4. 按enter键配置所有平台

   

5. 您现在应该有一个lib/firebase_options.dart文件。 将此文件导入您的main.dart并使用Firebase.initializeApp 。

    import 'firebase_options.dart'; void main() async { WidgetsFlutterBinding.ensureInitialized(); // This is the last thing you need to add. await Firebase.initializeApp( options: DefaultFirebaseOptions.currentPlatform, ); runApp(...); }

---

迁移到 Dart-only 初始化：

如果您已有现有应用程序，则可以通过以下方式迁移它。

• Android：

  1. 从<flutter-project>/android/app删除google-services.json文件：

     

  2. 删除<flutter-project>/android/build.gradle文件中的以下行

     

  3. 删除<flutter-project>/android/app/build.gradle文件中的以下行

     

• iOS

  打开Xcode中<flutter-project>/ios/Runner.xcworkspace文件，删除Runner中的GoogleService-Info.plist文件。

  

• 苹果系统

  打开Xcode中<flutter-project>/macos/Runner.xcworkspace文件，删除Runner中的GoogleService-Info.plist文件。

  

更多信息可以在这里找到

Answer 9

彼得的回答是完美的！ 但是，如果您在遵循Flutter Firebase codelab后仍然在代码中遇到错误，请注意这些教程截至 2020 年 8 月已过时且尚未更新。

您需要进行许多其他更改，例如：

• 用.data()替换.data
• 用更新updateData update数据

Answer 10

Flutter Web 与 Firebase

如果您将 Flutter Web 与 Firebase 一起使用，请确保将 SDK 安装在./web/index.html的body标签中

  <script src="https://www.gstatic.com/firebasejs/8.2.9/firebase-app.js"></script>
  <script src="https://www.gstatic.com/firebasejs/8.2.9/firebase-analytics.js"></script>

此外，请确保您也使用index.html中的配置参数调用firebase.initializeApp(...) 。

  <script>
    // Your web app's Firebase configuration
    // For Firebase JS SDK v7.20.0 and later, measurementId is optional
    var firebaseConfig = {
      apiKey: "AIz...",
      authDomain: "...",
      databaseURL: "https://<project-name>.firebaseio.com",
      projectId: "...",
      storageBucket: "<project-name>.appspot.com",
      messagingSenderId: "...",
      appId: "...",
      measurementId: "..."
    };
    firebase.initializeApp(firebaseConfig);
    firebase.analytics();
  </script>

最后按照Peter Haddad 的回答中的描述配置 firebase ：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

Answer 11

您需要添加await Firebase.initializeApp(); 这是一个Future 。 在运行 Firebase function 的 dart 文件中执行此操作，如下所示：

import 'package:firebase_core/firebase_core.dart';
...

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MaterialApp());
}

Answer 12

Since Flutter versions 2.8 , FlutterFire can now be initialized from Dart on all platforms using the Firebase.initializeApp function. There's a more simple and quicker way to initialize a firebase project, instead of downloading the.json and.plist file from the firebase console and将它们放入您的 Flutter 项目文件夹中，这可能会导致出现多个警告。 这是我遇到过好几次的问题，下面是我如何解决它的。

在此处的 firebase 控制台步骤中创建项目并在此处安装Firebase CLI 后，请继续执行以下步骤：

如果您已经使用 flutterfire configure 配置了 firebase 项目，则可以跳过第 1 步并跳到第 4 步。

1. 从您的项目根终端，命令：

    $ flutterfire configure // This requires the Firebase CLI to work.

2. Select firebase 项目按返回或输入。

3. 插入包 ID。 您可以通过右键单击 ios 文件夹 > 然后单击“在 xcode 中打开”来获取它。 Bundle Identifier 将出现在右侧的白色面板中，您必须在出现提示时在终端中手动输入它。

** 如果您已经安装了 firebase_core 插件，请继续执行第 5 步。 **

4. 通过从项目根目录运行此命令来安装最新版本的 firebase_core 插件：

    $ flutter pub add firebase_core // Adds to pubspec.yaml

5. 将导入添加到主文件：

    import 'package:firebase_core/firebase_core.dart'; // import 'firebase_options.dart'; // Generated file

6. 更新您的主 function 以使用此异步 function 初始化 firebase：

    Future<void> main() async { WidgetsFlutterBinding.ensureInitialized(); await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform); runApp(const YourAppName()); }

有关详细信息，请参阅 FlutterFire 文档。

Answer 13

如果当您将应用程序留在主屏幕时仍然遇到问题，您可以使用 Firebase 将其添加到任何.dart文件中：

class App extends StatelessWidget {

  final Future<FirebaseApp> _initialization = Firebase.initializeApp();

  @override
  Widget build(BuildContext context) {

或者在StatefulWidget的情况下：

import 'package:flutter/material.dart';

// Import the firebase_core plugin
import 'package:firebase_core/firebase_core.dart';

void main() {
  runApp(App());
}

class App extends StatefulWidget {
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {
  // Set default `_initialized` and `_error` state to false
  bool _initialized = false;
  bool _error = false;

  // Define an async function to initialize FlutterFire
  void initializeFlutterFire() async {
    try {
      // Wait for Firebase to initialize and set `_initialized` state to true
      await Firebase.initializeApp();
      setState(() {
        _initialized = true;
      });
    } catch(e) {
      // Set `_error` state to true if Firebase initialization fails
      setState(() {
        _error = true;
      });
    }
  }

  @override
  void initState() {
    initializeFlutterFire();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    // Show error message if initialization failed
    if(_error) {
      return SomethingWentWrong();
    }

    // Show a loader until FlutterFire is initialized
    if (!_initialized) {
      return Loading();
    }

    return MyAwesomeApp();
  }
}

有关更多信息，请查看此链接。

Answer 14

这是2022年初始化firebase的方法

首先，使用此链接安装 FlutterFire ==> Flutter Fire 安装链接

安装 FlutterFire 后，您需要在 lib/main.dart 文件中添加这些代码行

  import 'package:firebase_core/firebase_core.dart';
  import 'firebase_options.dart';  

然后编辑您的 Main Function，如下所示

void main() async {
 WidgetsFlutterBinding.ensureInitialized();
   await Firebase.initializeApp(options:                                  
   DefaultFirebaseOptions.currentPlatform,);
 runApp(MyApp()); 
 }

这在未来可能会发生变化，因此请参阅此链接以获取下面的最新实施参考

初始化 FlutterFire#

Answer 15

在大多数情况下，将项目从较旧的 Flutter 版本升级到 null 安全版本后会出现此问题。 这些东西应该检查：

确保你在 pubscpec.yaml 中有 firebase-core

导入firebase核心：

import 'package:firebase_core/firebase_core.dart';

在任何调用之前初始化 Firebase - 最好在 main.dart 内部，以便它在任何其他实现之前执行：

WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp(
  options: DefaultFirebaseOptions.currentPlatform,
);

来自官方文档。

Answer 16

将 firebase_core 依赖添加到您的 pubspec.yaml

然后在应用启动时初始化应用

void main() async {
  /// add this two lines
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  
   runApp(MyApp());
}

Answer 17

我需要使用 FlutterFire cli 重新配置 Firebase 应用程序。

https://firebase.flutter.dev/docs/cli

1. 通过 NPM 安装 firebase-tool: npm install -g firebase-tools
2. 安装flutterfire cli： dart pub global activate flutterfire_cli
3. 运行此命令以在您的项目中配置 firebase： flutterfire configure

按照上面的链接并初始化如下：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  runApp(const MyApp());
}

在等待调用时，该应用程序将显示启动画面，并且 Firebase 可能不会初始化，因此我接下来使用home屏幕的另一个 FutureBuilder 来确保在我使用 FirebaseAuth 之前初始化 Firebase 应用程序。

home: FutureBuilder(
          future: Firebase.initializeApp(),
          builder: (context, snapshot) {
            if (snapshot.hasError) {
              return Text(snapshot.error.toString(),
                  style: TextStyle(fontSize: 10));
            }

            if (snapshot.connectionState == ConnectionState.done) {
              return StreamBuilder(
                stream: FirebaseAuth.instance.authStateChanges(),
                builder: (context, snapshot) {
                  return snapshot.hasData ? Home() : AuthPage();
                },
              );
            } else {
              return Text('');
            }
          })

Answer 18

您也可以使用FutureBuilder在main.dart文件中进行初始化。

 future: Firebase.initializeApp(),

看看这个例子。

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      // Initialize FlutterFire
      future: Firebase.initializeApp(),
      builder: (context, snapshot) {
       return MaterialApp(
          debugShowCheckedModeBanner: false,
          title: 'NEWSAPI.org',
          home: SplashScreen(),
       
          routes: <String, WidgetBuilder>{
            SPLASH_SCREEN: (BuildContext context) => SplashScreen(),
          },);
      },
    );
  }
}

Answer 19

你需要在 main function 中添加await FirebaseApp.initializeApp()记得在 main function 中添加 await

Answer 20

如果您正确设置了 Firebase，请不要忘记添加

await

前

Firebase.initializeApp();

这主要是该异常的问题。

等待 Firebase.initializeApp();

Answer 21

就我而言，我为现有项目添加了 web 支持。 解决问题的一件事是，

在web/index.html文件中

将所有 firebase sdk 导入的verison从9.6.6更改为8.10.0

片段

<script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-app.js"></script>
  <script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-app-check.js"></script>  
  <script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-firestore.js"></script>
  <script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-auth.js"></script>
  <script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-storage.js"></script>
  <script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-messaging.js"></script>
 <script>
  var firebaseConfig = {
   ....
   }

Answer 22

如果您正在处理一个预先配置了 firebase_core 的项目，然后您尝试添加新包，则会出现该错误。

您必须先从 pubsec.yaml 中删除 firebase_core firebase_core: ，然后保存文件并通过flutter pub add firebase_core和flutterfire configure 。

然后您可以添加任何新包。

Answer 23

永远记住，firebase 在您的项目中仅初始化一次，因此您在主 class 中使用，因为如果应用程序打开，主 class 仅调用一次

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  runApp(MyApp());
}

Answer 24

使用 firebase 选项初始化

void main() async{
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
  options: DefaultFirebaseOptions.currentPlatform).catchError((e){
    print(" Error : ${e.toString()}");
  });
}

Answer 25

试试下面的代码。 它将解决 IOS 和 Android 的问题。

import 'dart:io';
import 'package:firebase_core/firebase_core.dart';

    void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  if (Platform.isIOS) {
    await Firebase.initializeApp(
      options: const FirebaseOptions(
          apiKey: "found in your google service-info.plist",
          appId: "found in your google service-info.plist",
          messagingSenderId: "found in firebase",
          projectId: "found in firebase"),
    );
  } else {
    await Firebase.initializeApp();
  }
  runApp(const MyApp());
}

Answer 26

就我而言，这是因为对于 Web 版本，您必须在index.html文件中手动添加内容，不仅是 .js 依赖项，还有配置。 请参阅Web 安装。

我们往往会忘记，对于大多数内容，Flutter 已编译到目标，无需更改任何特定于目标的内容，但在这种情况下，必须为每个目标添加配置。

Answer 27

将此用于 flutter：

   const firebaseConfig = {

    apiKey: "",
    authDomain: "",
    projectId: "",
    storageBucket: "",
    messagingSenderId: "",
    appId: "",
    measurementId: ""
    };
   
  // Initialize Firebase
  firebase.initializeApp(firebaseConfig);
  firebase.getAnalytics(app);

而不是这个

   const firebaseConfig = {

    apiKey: "",
    authDomain: "",
    projectId: "",
    storageBucket: "",
    messagingSenderId: "",
    appId: "",
    measurementId: ""
    };

    // Initialize Firebase
    const app = initializeApp(firebaseConfig);
    const analytics = getAnalytics(app);

Answer 28

在文件main.dart 中，您必须添加依赖项import 'package:firebase_core/firebase_core.dart'; 并调用Firebase.initializeApp()方法如下：

//import the dependencie 
import 'package:firebase_core/firebase_core.dart';

//modify the main method
void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();
    runApp(const MyApp());
}

Answer 29

我想发表评论。 但是这个问题有很多线索。 对于我的情况。

我在 Firebase 之前初始化注入容器。需要检查层次结构。

Hive.init(directory.path);
  await Firebase.initializeApp();// before
  await di.init();

Answer 30

首先导入firebase_core插件，生成firebase_options.dart文件：

import 'package:firebase_core/firebase_core.dart';
import 'firebase_options.dart';

接下来，在main function 中，确保WidgetsFlutterBinding已初始化，然后初始化 Firebase：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );
  runApp(MyApp());
}

DefaultFirebaseOptions.currentPlatform是从我们生成的firebase_options.dart文件中导入的。

这是完整的例子

// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'package:firebase_core_example/firebase_config.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  String get name => 'foo';

  FirebaseOptions get firebaseOptions => const FirebaseOptions(
        appId: '1:448618578101:ios:0b650370bb29e29cac3efc',
        apiKey: 'AIzaSyAgUhHU8wSJgO5MVNy95tMT07NEjzMOfz0',
        projectId: 'react-native-firebase-testing',
        messagingSenderId: '448618578101',
      );

  Future<void> initializeDefault() async {
    FirebaseApp app = await Firebase.initializeApp(
      options: DefaultFirebaseConfig.platformOptions,
    );
    print('Initialized default app $app');
  }

  Future<void> initializeSecondary() async {
    FirebaseApp app =
        await Firebase.initializeApp(name: name, options: firebaseOptions);

    print('Initialized $app');
  }

  void apps() {
    final List<FirebaseApp> apps = Firebase.apps;
    print('Currently initialized apps: $apps');
  }

  void options() {
    final FirebaseApp app = Firebase.app(name);
    final options = app.options;
    print('Current options for app $name: $options');
  }

  Future<void> delete() async {
    final FirebaseApp app = Firebase.app(name);
    await app.delete();
    print('App $name deleted');
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Firebase Core example app'),
        ),
        body: Padding(
          padding: const EdgeInsets.all(20),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: <Widget>[
              ElevatedButton(
                onPressed: initializeDefault,
                child: const Text('Initialize default app'),
              ),
              ElevatedButton(
                onPressed: initializeSecondary,
                child: const Text('Initialize secondary app'),
              ),
              ElevatedButton(
                onPressed: apps,
                child: const Text('Get apps'),
              ),
              ElevatedButton(
                onPressed: options,
                child: const Text('List options'),
              ),
              ElevatedButton(
                onPressed: delete,
                child: const Text('Delete app'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Answer 31

使用 firebase 选项初始化

void main() async{
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp(
options: DefaultFirebaseOptions.currentPlatform).catchError((e){
  print(" Error : ${e.toString()}");
});
}

像这样

Answer 32

正确的方法是：为我工作 调试和发布模式都可以正常工作 在您的项目中仅使用 firebase 选项初始化一次

void main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
runApp(MyApp());}

Answer 33

确保您使用的是 firebase package 的正确/官方版本。

我正在使用：

firebase_core_dart: <version-number>

在： https://pub.dev/packages/firebase_core_dart

而不是官方

firebase_core: <version-number>

在https://pub.dev/packages/firebase_core

使用第一个选项，我在使用时得到了初始化：

await Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  ).whenComplete(
      () => print('FIREBASE INITIALIZED================>'));

但身份验证失败，并显示 OP 描述的错误消息。

Answer 34

对我来说问题是我在没有“等待”的情况下初始化了它：

void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    Firebase.initializeApp();

正确的做法是：

void main() async {
    WidgetsFlutterBinding.ensureInitialized();
    await Firebase.initializeApp();