Provider

A relatively simple and efficient tool for state management in Flutter is provider.

Usage⚑

ChangeNotifierProxyProvider⚑

When an provider needs information from another, use ChangeNotifierProxyProvider.

class MyModel with ChangeNotifier {
  ...
  }

}
class MyChangeNotifier with ChangeNotifier {
  void update(MyModel myModel) {
    // Do some custom work based on myModel that may call `notifyListeners`
  }
}

ChangeNotifierProxyProvider<MyModel, MyChangeNotifier>(
  create: (_) => MyChangeNotifier(),
  update: (_, myModel, myNotifier) => myNotifier
    ..update(myModel),
  child: ...
);

Pass the provider dependency as the first argument, which must be declared already (e.g., as a ChangeNotifierProvider in a MultiProvider).