Can't access to get_It when the app in background state

Plugins & Packages get_it, watch_it, flutter_command
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1

I am using Firebase Cloud Messaging with a background message handler, annotated with @pragma(‘vm:entry-point’), in my Flutter app. Inside the background handler, I call getIt as my service locator to obtain the injected AudioPlayer instance. However, I encounter the following error:

An error occurred in your background messaging handler:
Bad state: GetIt: Object/factory with type AudioPlayer is not registered inside GetIt.
(Did you accidentally do GetIt sl=GetIt.instance(); instead of GetIt sl=GetIt.instance;
Did you forget to register it?)
I have registered AudioPlayer with GetIt and injectable, and it works fine in the foreground state handler for Firebase setup. My dependency injection is set up as follows:

Injection file:

final getIt = GetIt.instance;

@InjectableInit()
Future<void> configureDependencies() => getIt.init();

Dependency Module:

@module
abstract class CoreModule {
  @lazySingleton
  AudioPlayer get audioPlayer => AudioPlayer();
  // Other dependencies...
}

Firebase Messaging Setup:

FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

Background Handler:

@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage notificationResponse) async {
  final audioPlayer = getIt<AudioPlayer>();
  // Additional code...
}
2

The reason is that the this callback is called on a different isolate than your already background app. All variables live only in the isolate where they are created and you can’t access a variable from a different isolate.

why don’t you call configureDependencies at the beginning of your handler so that all your dependencies are registered in this isolate.

3 Likes
3

because I need to access to that instance that is injected in the main isolate and that appears impossible, so in this case I will search for another solution
thank you a lot @escamoteur

4

As it won’t be possible to do that directly you could save needed data to share_preferences when your app is being suspened for example and read it back inside the callback

1 Like
5

how to access to shared preferences in the firebase background handler
because I am injecting it too with getIt

@module
abstract class CoreModule {
  @lazySingleton
  http.Client get httpClient => http.Client();

  @preResolve
  Future<AppDatabase> get database =>
      $FloorAppDatabase.databaseBuilder('app_database.db').build();

  @preResolve
  Future<SharedPreferences> get sharedPreferences =>
      SharedPreferences.getInstance();

  @lazySingleton
  AudioPlayer get audioPlayer => AudioPlayer();

  @lazySingleton
  InternetConnectionChecker get dataConnectionChecker =>
      InternetConnectionChecker();
}
6

just use it directly inside the handler. no need to inject it

2 Likes
7

thanks for the ida Maan :heart_eyes:
but I can’t save AudioPlayer instance with SharedPreferences

8

no you probably have to recreate a new instance of the audioplayer in that case or you have to find out how to wakeup your full app from that handler.

2 Likes