CODEWITHSUNDEEP
flutterriverpod
Zeffry Reynando
Zeffry Reynando

Reputation: 3899

Flutter Riverpod : The member 'state' can only be used within instance members of subclasses of 'package:state_notifier/state_notifier.dart'

I have simple example about toggle widget,my expectation after click button i show circularProgressIndicator then after 3 second i showing Text. For my example i use riverpod_hooks and flutter_hooks.

LoadingProvider

class IsLoading extends StateNotifier<bool> {
  IsLoading() : super(false);
  void toggleLoading(bool value) => state = value;
}

final isLoadingProvider = StateNotifierProvider((ref) => IsLoading());

Main.dart

class TestingApp extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final IsLoading isLoading = useProvider(isLoadingProvider);
    return Scaffold(
      body: Container(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Center(
              child: isLoading.state ? CircularProgressIndicator() : Text('This Is Your Data'),
            ),
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: FlatButton(
                  onPressed: () => showLoading(isLoading), child: Text('Toggle Loading')),
            ),
          ],
        ),
      ),
    );
  }

  void showLoading(IsLoading isLoading) async {
    isLoading.toggleLoading(true);
    print("Proses");
    await Future.delayed(const Duration(seconds: 3));
    print("Done");
    isLoading.toggleLoading(false);
  }
}

But when i press the button , it's not show progressIndicator and still showing the text and i got this warning :
The member 'state' can only be used within instance members of subclasses of 'package:state_notifier/state_notifier.dart'.

I missed something ?

My source code following the documentation like this :

enter image description here

Upvotes: 6

Views: 5511

Answers (2)

Yves Boutellier
Yves Boutellier

Reputation: 2034

Provide two types for your StateNotifierProvider, the type of class you are returning and the state the class has.

class IsLoading extends StateNotifier<bool> {
  IsLoading() : super(false);
  void toggleLoading(bool value) => state = value;
}

final isLoadingProvider =
    StateNotifierProvider<IsLoading, bool>((ref) => IsLoading());

in your build method (of a ConsumerStateWidget) use:

final isLoading = ref.watch(isLoadingProvider);
return Scaffold(body: Center(child:
isLoading ? CircularProgressIndicator() : Text('This Is Your Data'),))

Upvotes: 1

Mohammed Abd Elsamad
Mohammed Abd Elsamad

Reputation: 11

It says right there that it won’t trigger the method to rebuild when you call increment like that.

so instead of isLoading.toggleLoading(true) call with a read method so it can rebuild the state like that isLoading.read(context).toggleLoading(true)

Upvotes: 1

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