Double Notifications in Flutter firebase messaging

Question

Recently I upgraded to firebase_messaging: ^10.0.0 When app is in not running and if notification comes it is displaying twice. I modified the notification data in code after receiving and displayed it. Even then I can see the modified and non modified notifications. I don't know where that notification is triggering. But when app is running it is displaying notification once only(works fine). Here goes my code

/*main.dart*/
Future firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // If you're going to use other Firebase services in the background, such as Firestore,
  // make sure you call `initializeApp` before using other Firebase services.
  //await Firebase.initializeApp();

  // await HomePageState.handleMessage(message);
  String title="${message.notification!.title}";
  String body="${message.notification!.body}";

  _flutterLocalNotificationsPlugin.show(0, title, body, platformChannelSpecifics, payload: jsonEncode(message.data));

  AppDatabase database= await $FloorAppDatabase.databaseBuilder(Constants.dataBaseName).addMigrations([migration1to2]).build();
  if(!title.toLowerCase().contains("cancelled")){
    var date=DateFormat("dd-MMM-yyyy hh:mm aa").format(DateTime.now());
    NotificationModel notification=NotificationModel(title: title,message: body,read: 0,date: date);
    await database.notificationDao.insertNotification(notification);
  }

  print("Handling a background message: ${message.messageId}");
}
Future main() async {
  //this line make sure all the required widgets are loaded before main application starts
  //SharedPreferences.setMockInitialValues({});
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();

  var initializationSettingsAndroid = new AndroidInitializationSettings('@mipmap/ic_notification');
  var initializationSettingsIOS = new IOSInitializationSettings(onDidReceiveLocalNotification: onDidReceiveLocalNotification);
  //var initializationSettings = new InitializationSettings(initializationSettingsAndroid, initializationSettingsIOS);
  var initializationSettings = new InitializationSettings(android: initializationSettingsAndroid,iOS: initializationSettingsIOS);
  _flutterLocalNotificationsPlugin.initialize(initializationSettings,onSelectNotification: onSelectingNotification);

  FirebaseMessaging.onBackgroundMessage(firebaseMessagingBackgroundHandler);


  //Initializing repository and carrying forward to avoid multiple instances of database
  Repository _repository = Repository();

  // runApp(BlocProvider(
  //   create: (_) => ThemeBloc()..add(ThemeLoadStarted()),
  //   child: MyApp(
  //     repository: _repository,
  //   ),
  // ));
  SentryOptions options=SentryOptions(dsn: APIs.sentryAPI);
  final SentryClient _sentry = SentryClient(options);

  Future _reportErrorToSentry(dynamic error, dynamic stackTrace) async {
    // Print the exception to the console.
    print('Caught error: $error');
   await  _sentry.captureException(
      error,
      stackTrace: stackTrace,
    );
  }

  runZonedGuarded(() async{
    // runApp(BlocProvider(
    //   create: (_) => ThemeBloc()..add(ThemeLoadStarted()),
    //   child: MyApp(
    //     repository: _repository,
    //   ),
    // ));

    await SentryFlutter.init(
          (options) => options.dsn = APIs.sentryAPI,
      appRunner: () => runApp(BlocProvider(
        create: (_) => ThemeBloc()..add(ThemeLoadStarted()),
        child: MyApp(
          repository: _repository,
        ),
      )),
    );
  }, (error, stackTrace) {
    print('runZonedGuarded: Caught error in my root zone.');
    FirebaseCrashlytics.instance.recordError(error, stackTrace);
    _reportErrorToSentry(error,stackTrace);
  });

}

Application.kt

import io.flutter.app.FlutterApplication
import io.flutter.plugin.common.PluginRegistry
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback
import io.flutter.plugins.GeneratedPluginRegistrant
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingBackgroundService


class Application : FlutterApplication(), PluginRegistrantCallback {

    override fun registerWith(registry: PluginRegistry) {
        //FirebaseCloudMessagingPluginRegistrant.registerWith(registry)
        FlutterLocalNotificationPluginRegistrant.registerWith(registry)
        SqflitePluginRegistrant.registerWith(registry)
    }
}

FirebaseCloudMessagingPluginRegistrant.kt which I commented out in application.kt

import io.flutter.plugin.common.PluginRegistry
import io.flutter.plugins.firebase.messaging.FlutterFirebaseMessagingPlugin
class FirebaseCloudMessagingPluginRegistrant {
    companion object {
        fun registerWith(registry: PluginRegistry) {
            if (alreadyRegisteredWith(registry)) {
                return
            }
            FlutterFirebaseMessagingPlugin.registerWith(registry.registrarFor("io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin"))
        }

        fun alreadyRegisteredWith(registry: PluginRegistry): Boolean {
            val key = FirebaseCloudMessagingPluginRegistrant::class.java.name
            if (registry.hasPlugin(key)) {
                return true
            }
            registry.registrarFor(key)
            return false
        }
    }
}

AndroidManifest.xml

This issue is in android only that too when app is not running. Where am I doing wrong?

user_11039164 · Answer

It appears you're sending a "notification" message from Firebase Messaging when you should be sending a "data" message.

Here is the difference between a notification message and a data message:

Notification message

FCM automatically displays the message to end-user devices on behalf of the client app.

Data message

Client app is responsible for processing data messages.

About FCM Messages | Firebase (#Message types)

That explains why you get the unmodified version of the notification (this is from the automatic display of the notification message) and the modified version of the notification (this is from your own code where you handle the notification).

Solution:

You need to send a data message from your backend. So if you had this before as your notification payload:

{
  "message":{
    "token":"bk3RNwTe3H0:CI2k_HHwgIpoDKCIZvvDMExUdFQ3P1...",
    "notification":{
      "Nick" : "Mario",
      "body" : "great match!",
      "Room" : "PortugalVSDenmark"
    }
  }
}

you should change it to:

{
  "message":{
    "token":"bk3RNwTe3H0:CI2k_HHwgIpoDKCIZvvDMExUdFQ3P1...",
    "data":{
      "Nick" : "Mario",
      "body" : "great match!",
      "Room" : "PortugalVSDenmark"
    }
  }
}

Double Notifications in Flutter firebase messaging

1 Answers