未处理的异常：[core/no-app] 未创建 Firebase 应用程序“[DEFAULT]” - 调用 Firebase.initializeApp()

Question

我在main内部初始化了Firebase，需要在workmanager内部访问用户数据，为用户提供个性化通知，但workmanager由于某种原因与Firebase初始化同时同步工作，所以导致了这个问题。

我尝试添加一个像这样的简单if语句来解决问题，并添加两次初始化，一次用于main，一次用于工作管理器，但并没有解决问题。

输出启动 firebase 初始化打印了两次并且出现此错误： lStateException：FirebaseApp 名称 [DEFAULT] 已存在！，IllegalStateException，原因：null，Stacktrace：java.lang.IllegalStateException：FirebaseApp 名称 [DEFAULT] 已存在！

 // AuthService code
 // initialize firebase
        static Future initializeFirebase() async {
          if (!isInitialized && Firebase.apps.isEmpty) {
            print('start firebase initializion');
            await Firebase.initializeApp(
              options: DefaultFirebaseOptions.currentPlatform,
            );
            isInitialized = true;
          } else {
            print('firebase is already initialized');
          }
        }
    ...
      /////////////////////////////////////////////////////////////
      //here is main code:

      Future<void> main() async {
        // initialize firebase
        WidgetsFlutterBinding.ensureInitialized();
        await AuthService.initializeFirebase();

        // preferred screen orientations
        SystemChrome.setPreferredOrientations(
            [DeviceOrientation.portraitUp, DeviceOrientation.portraitDown]);

        // initialize notifications
        NotificationService().initNotification();

        //initialize workmanager
        Workmanager().initialize(callbackDispatcher);

      ...



      void callbackDispatcher() async {
        print('entered...');
        // initialize firebase
        WidgetsFlutterBinding.ensureInitialized();
        await AuthService.initializeFirebase();

        //////////// access data for notification ////////////////
        final user = FirebaseAuth.instance.currentUser;
        String uid = user!.uid;
        //child collection
        final CollectionReference childCollection =
            FirebaseFirestore.instance.collection('child');

        //morning collection
        CollectionReference schedule_morning =
            childCollection.doc(uid).collection('schedule_morning');
        final QuerySnapshot morning_tasks = await schedule_morning.get();

        //noon collection
        CollectionReference schedule_noon =
            childCollection.doc(uid).collection('schedule_noon');
        final QuerySnapshot noon_tasks = await schedule_noon.get();

        //night collection
        CollectionReference schedule_night =
            childCollection.doc(uid).collection('schedule_night');
        final QuerySnapshot night_tasks = await schedule_night.get();

        //to get user name
        final DocumentSnapshot userDoc = await childCollection.doc(uid).get();
        if (userDoc.exists) {
          Map<String, dynamic> userData = userDoc.data() as Map<String, dynamic>;
          final String userName = userData['name']; 

      // notify the user
      if (DateTime.now().hour == 06 && morning_tasks.size > 0) {
            Workmanager().executeTask((taskName, inputData) {
              NotificationService().showNotification(
                title: 'todays tasks',
                body: '$userName do not forget your morning tasks',
              );
              return Future.value(true);
            });
          }
...

Answer 1

首先，您不必手动检查 firebase 是否已初始化。所以只需调用该函数一次即可。

  await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);

要解决您的问题，请从项目根文件夹运行这些命令，

flutter pub add firebase_core firebase_messaging

# Install the CLI if not already done so
dart pub global activate flutterfire_cli

# Run the `configure` command, select a Firebase project and platforms
flutterfire configure

欲了解更多信息，请访问此链接。