Flutter Mobx Observer doesnt rebuild

Question

I have no Idea anymore.

I am using Mobx for really simple State Management.

import 'package:flutter/material.dart';
import 'package:flutter_mobx/flutter_mobx.dart';
import 'package:jw_helper/state/globalState.dart';

class Router extends StatelessWidget {
  const Router({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final _globalState = GlobalState();
    return Column(
      children: <Widget>[
        Container(
          child: Observer(
            builder: (_) => Text(_globalState?.currentIndex?.toString()),
          ),
        ),
        MaterialButton(
          onPressed: () {
            _globalState.setCurrentIndex(1);
          },
          child: Text("Press me"),
        ),
      ],
    );
  }
}

When i mutate the state in this widget the value updates. When i mutate the same Observable in another Widget the Observer is not rebuilding.

Only the observer in the same Widget where the State is mutated is updated.

My Mobx Code:

import 'package:mobx/mobx.dart';

// Include generated file
part 'globalState.g.dart';

// This is the class used by rest of your codebase
class GlobalState = _GlobalState with _$GlobalState;

// The store-class
abstract class _GlobalState with Store {
  @observable
  int currentIndex = 0;

  @action
  void setCurrentIndex(index) {
    currentIndex = index;
    print(currentIndex);
  }
}

Small note: The Print Statement is always fired

Maybe someone knows how to fix this. Thank you ;)

Answer 1

The Problem was solved with Help from a Discord Mobx Channel Member.

The solution was to wrap the whole App in a provider Widget.

class MyApp extends StatelessWidget {
  @override
    Widget build(BuildContext context) {
------------------------------------------------
    return Provider<GlobalState>(
      create: (context) => GlobalState(),
------------------------------------------------
      child: MaterialApp(
        title: 'Flutter Demo',
        debugShowCheckedModeBanner: false,
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: SplashScreen(),
      ),
    );
  }
}

In the Widgets consuming the Mobx Class i did:

class Router extends StatelessWidget {
  const Router({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final _globalState = Provider.of<GlobalState>(context);
    return Column(
      children: <Widget>[
        Container(.....

Hopefully this helps somebody to get up and running ;)