How to use onBackgroundMessage in flutter with firebase (FCM), The onBackgroundMessage is not getting triggered

Question

I want to store the incoming firebase message in a database locally and its working fine for onMessage , onLaunch and onResume but the onBackgroundMessage is not getting triggered at all when i try to debug but when my app is in background i am able to get the notification in the notification tray

Push Notification

Future<dynamic> backgroundMessageHandler(Map<String, dynamic> message) async {
  if (message.containsKey('data')) {
    print({message});
    PushNotificationService().storeInDatabase(message);
    final notifications = await PushNotificationService().getNotifications();
    final reversedNotifications = notifications.reversed.toList();
    homeScreenBloc.activityController.add(reversedNotifications);
  }
}

class PushNotificationService {
  BuildContext context;

  final FirebaseMessaging _fcm = FirebaseMessaging();

  Future initialise() async {
// print('notifcations length = ${notifications.length}');
// context = ctx;
    final notifications = await getNotifications();
    if (notifications != null) {
      homeScreenBloc.activityController.add(notifications);
    }
    if (Platform.isIOS) {
      _fcm.requestNotificationPermissions(IosNotificationSettings());
    }

    _fcm.configure(
      onMessage: (Map<String, dynamic> message) async {
        print({message});
        storeInDatabase(message);
        final notifications = await getNotifications();
        final reversedNotifications = notifications.reversed.toList();
        homeScreenBloc.activityController.add(reversedNotifications);
      }

      /// called when the notification is clicked while the app is in running in foreground
      /// notification fields sends title and body but for other two cases its blank
      /// so need to send in data field

      ,
// called when the notification is clicked while the app is closed(not running)
      onLaunch: (Map<String, dynamic> message) async {
        print({message});
        storeInDatabase(message);
        final notifications = await getNotifications();
        final reversedNotifications = notifications.reversed.toList();
        homeScreenBloc.activityController.add(reversedNotifications);
      },
// called when the notification is clicked while the app is running in the background
      onResume: (Map<String, dynamic> message) async {
        print({message});
        storeInDatabase(message);
        final notifications = await getNotifications();
        final reversedNotifications = notifications.reversed.toList();
        homeScreenBloc.activityController.add(reversedNotifications);
      },
      // called while the app is running in the background
      onBackgroundMessage: Platform.isIOS ? null : backgroundMessageHandler,
      // }
    );
  }

AndroidManifest.xml

 <application android:usesCleartextTraffic="true" android:name=".Application" ....

Application.kt

package com.altorumleren.alfinityiot;

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.firebasemessaging.FlutterFirebaseMessagingService;

public class Application extends FlutterApplication implements PluginRegistrantCallback {
  @Override
  public void onCreate() {
    super.onCreate();
    FlutterFirebaseMessagingService.setPluginRegistrant(this);
  }

  @Override
  public void registerWith(PluginRegistry registry) {
    GeneratedPluginRegistrant.registerWith(registry);
  }
}

build.gradle

dependencies {
    implementation 'com.google.firebase:firebase-messaging:<21.0.0>'
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.google.firebase:firebase-analytics:17.2.2'
    implementation "com.google.firebase:firebase-messaging:20.2.4"
}

Logs when I am running the app

Launching lib\main.dart on AOSP on IA Emulator in debug mode...
lib\main.dart:1
registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
registerResGeneratingTask is deprecated, use registerGeneratedResFolders(FileCollection)
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (9, 26): Expecting a top level declaration
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (9, 34): Expecting a top level declaration
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (9, 53): Expecting a top level declaration
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (9, 64): Expecting a top level declaration
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (9, 89): Expecting a top level declaration
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (9, 89): Function declaration must have a name
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (17, 51): Expecting an element
e: C:\Users\adity\Desktop\alfinity\android\app\src\main\kotlin\com\example\alfinity\Application.kt: (10, 3): This annotation is not applicable to target 'expression'

Answer 1

Seems like you didn't mention about your payload but in order to trigger onBackgroundMessege you need to make sure that your payload doesn't contain notification. For example:

    const payload = {
        data: {
            title: 'title',
            body: 'body',
        }
    }