Flutter Global Function update Stateful Widget State

Question

I am writing a Flutter app that uses a Global Function to handle Pushy.me notifications. This function needs to update a stateful widget's state.

I have tried a Global Key to access the widgets current state but it did nothing. I have tried an Eventify emitter, the emit and the listener didnt seem to line up.

import 'package:eventify/eventify.dart';

EventEmitter emitter = new EventEmitter();
GlobalKey<_WrapperScreenState> _key = GlobalKey<_WrapperScreenState>();

void backgroundNotificationListener(Map<String, dynamic> data) {
  // Print notification payload data
  print('Received notification: $data');

  // Notification title
  String notificationTitle = 'MyApp';

  // Attempt to extract the "message" property from the payload: {"message":"Hello World!"}
  String notificationText = data['message'] ?? 'Hello World!';

  Pushy.notify(notificationTitle, notificationText, data);
  emitter.emit('updateList',null,"");
  try{
    print(_key.currentState.test);
  }
  catch(e){
    print(e);
  }
  // Clear iOS app badge number
  Pushy.clearBadge();
}
class WrapperScreen extends StatefulWidget {
  @override
  _WrapperScreenState createState() => _WrapperScreenState();
}

Answer 1

You can try using events for this, using a StreamController or the event bus package. Your stateful widget would listen on a global event bus, and you can fire an event with the necessary information for the widget itself to use to update the state.

Something like this (using the event bus package):

// main.dart

EventBus eventBus = EventBus();


class MyEvent {}

void somewhereGlobal() {
    // trigger widget state change from global location
    eventBus.fire(MyEvent());
}


void main() {

...

}

// my_stateful_widget.dart
...

class _MyWidgetState extends State<MyWidget> {
  @override
  void initState() {
    super.initState();
    eventBus.on<MyEvent>().listen((event) {
      // update widget state
      print("update widget state");
    });
  }

...