Flutter Riverpod #

dependencies:
  flutter_riverpod: ^2.4.9

final counterProvider = StateProvider<int>((ref) => 0);

void main() {
  runApp(ProviderScope(child: MyApp()));
}

class MyApp extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final count = ref.watch(counterProvider);
    
    return MaterialApp(
      home: Scaffold(
        body: Center(child: Text('$count')),
        floatingActionButton: FloatingActionButton(
          onPressed: () => ref.read(counterProvider.notifier).state++,
          child: Icon(Icons.add),
        ),
      ),
    );
  }
}

final counterProvider = StateProvider<int>((ref) => 0);

ref.watch(counterProvider);
ref.read(counterProvider.notifier).state = 10;

class Counter extends StateNotifier<int> {
  Counter() : super(0);
  
  void increment() => state++;
  void decrement() => state--;
}

final counterProvider = StateNotifierProvider<Counter, int>((ref) => Counter());

ref.watch(counterProvider);
ref.read(counterProvider.notifier).increment();

final dataProvider = FutureProvider<String>((ref) async {
  await Future.delayed(Duration(seconds: 1));
  return 'Data loaded';
});

ref.watch(dataProvider).when(
  data: (data) => Text(data),
  loading: () => CircularProgressIndicator(),
  error: (error, stack) => Text('Error: $error'),
);

final streamProvider = StreamProvider<int>((ref) {
  return Stream.periodic(Duration(seconds: 1), (count) => count);
});