Flutter: Can't use any plugin in onBackgroundMessage

Question

I am using Firebase Push Notifications and I want to execute some of my code when onBackgroundMessage is triggered. It actually gets triggered because I print in console, but I tried to use several plugins and no luck. I get error every time something like (Unhandled Exception: MissingPluginException(No implementation found for method play on channel flutter_ringtone_player)). I believe this is because there is no context of application in background state of application, but what is this function good for then and what can I actually do in it?

I would like to play sound when onBackgroundMessage is triggered.

    super.initState();

    _firebaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        print("onMessage: $message");
      },
      onBackgroundMessage: myBackgroundMessageHandler,
      onLaunch: (Map<String, dynamic> message) async {
        print("onLaunch: $message");
      },
      onResume: (Map<String, dynamic> message) async {
        print("onResume: $message");
      },
    );

static Future<dynamic> myBackgroundMessageHandler(Map<String, dynamic> message) async {        
  FlutterRingtonePlayer.play(
    android: AndroidSounds.notification,
    ios: IosSounds.glass,
    looping: true, // Android only - API >= 28
    volume: 0.8, // Android only - API >= 28
    asAlarm: true, // Android only - all APIs
  );

    print("background message executed");

  return null;
}

Answer 1

Try registering the plugins that you need to use in myBackgroundMessageHandler in your Android's Application class. Here is an example of my Application.kt:

class Application : FlutterApplication(), PluginRegistrantCallback {
override fun onCreate() {
    super.onCreate()
    FlutterFirebaseMessagingService.setPluginRegistrant(this)
}

override fun registerWith(registry: PluginRegistry?) {
    PathProviderPlugin.registerWith(registry?.registrarFor("io.flutter.plugins.pathprovider.PathProviderPlugin"))
    FlutterLocalNotificationsPlugin.registerWith(registry?.registrarFor("com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin"))
    FirebaseCloudMessagingPluginRegistrant.registerWith(registry)
}
}