How to use method from one Change notifier class in another change notifier class provider

Question

I want to use fetchdata() in another provider method and initialise variables.

Answer 1

you can use MultiProvider with ChangeNotifierProxyProvider

1. Action Class ( FirstModel )

    class FirstModel with ChangeNotifier {
    List<Strings> _names = ["Sat", "Sat2", "Sat3"];
   
    List<Strings> get names {
       return _names ;
    }
    }
   

2. Action Class ( SecondModel )

    class SecondModel with ChangeNotifier {        
    SecondModel(this.firstModel);
   
    final FirstModel firstModel;
    List<Strings> getNames(){
       return firstModel.names;
    }
    }
   

In main.dart just update the Multiprovider, example below

void main() {
  runApp(
    MultiProvider(
      providers: [
        ChangeNotifierProvider<FirstModel>(create: (_) => FirstModel()),
        ChangeNotifierProxyProvider0<SecondModel>(
          create: (BuildContext context) =>
              SecondModel(Provider.of<FirstModel>(context, listen: false)),
          update: (BuildContext context, SecondModel secondModel) =>
              SecondModel(Provider.of<FirstModel>(context, listen: false)),
        ),
      ],
      child: MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyHomePage(),
    );
  }
}

Similar other class also avilable... For More Information please refer below link...

ChangeNotifierProxyProvider0 class API

Answer 2

If someone still has difficulties with this then maybe this will help:

Accessing one provider method into another provider:-

class 1:-

class OneState extends ChangeNotifier {

  List<Strings> _names = ["Alex", "Brad", "Carol"];
  List<GlobalKey> get names=> _names;

  updateNames(
      {required List<Strings> names}) {
    _names = names;

    notifyListners();
  }

}

class 2:-

class AnotherState extends ChangeNotifier {

  AnotherState({required this.watchOneStateProviderValue}); //<- Notice this.

  OneState watchOneStateProviderValue; //<- Notice this.

  late List<int> _iq;
  List<GlobalKey> get iq=> _iq;

  createIQFromNames() {

     // Getting names from another provider.
     List<String> names = watchOneStateProviderValue.names; //<- Notice this.

     _iq = [];
     for(var name in names){
       if(name == "Park Ju-hyun"){
         iq.add(99999);
       } else {
         iq.add(0);
       }
     }

     notifyListners();
  }
}

Now declare providers like this:-

final oneStateProvider =
    ChangeNotifierProvider((ref) => OneState());

final anotherStateProvider = ChangeNotifierProvider((ref) {
  // We use `ref.watch` to watch another provider, and we pass it the provider
  // that we want to consume. Here: oneStateProvider
  final CalendarPropertiesState watchCalendarPropertiesStateProviderValue =
      ref.watch(calendarPropertiesStateProvider);

  // We can then use the result to do something based on the value of `oneStateProvider`.
  return AnotherState(watchOneStateProviderValue: watchOneStateProviderValue);
});

Answer 3

var prevProvider = Provider.of<PrevProvider>(context, listen: false);
await prevProvider.fetchdata();

Hope it will work