State Management في Flutter: Provider، Riverpod، BLoC

flutter pub add provider

flutter pub add flutter_riverpod

flutter pub add flutter_bloc

import 'package:flutter/foundation.dart';

class Counter extends ChangeNotifier {
  int _count = 0;
  int get count => _count;

  void increment() {
    _count++;
    notifyListeners(); // يُخبر المستمعين
  }
}

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (_) => Counter(),
      child: const MyApp(),
    ),
  );
}

class CounterView extends StatelessWidget {
  const CounterView({super.key});

  @override
  Widget build(BuildContext context) {
    final counter = context.watch<Counter>();
    return Column(
      children: [
        Text('${counter.count}'),
        ElevatedButton(
          onPressed: () => context.read<Counter>().increment(),
          child: const Text('+1'),
        ),
      ],
    );
  }
}

// تعريف الـ provider
final counterProvider = StateProvider<int>((ref) => 0);

// التطبيق (لفّ الـ root)
void main() {
  runApp(const ProviderScope(child: MyApp()));
}

// الاستهلاك
class CounterView extends ConsumerWidget {
  const CounterView({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final count = ref.watch(counterProvider);
    return Column(
      children: [
        Text('$count'),
        ElevatedButton(
          onPressed: () => ref.read(counterProvider.notifier).state++,
          child: const Text('+1'),
        ),
      ],
    );
  }
}

// الأحداث
abstract class CounterEvent {}
class Increment extends CounterEvent {}
class Decrement extends CounterEvent {}

// الـ Bloc
class CounterBloc extends Bloc<CounterEvent, int> {
  CounterBloc() : super(0) {
    on<Increment>((event, emit) => emit(state + 1));
    on<Decrement>((event, emit) => emit(state - 1));
  }
}

void main() {
  runApp(
    BlocProvider(
      create: (_) => CounterBloc(),
      child: const MyApp(),
    ),
  );
}

// الواجهة
BlocBuilder<CounterBloc, int>(
  builder: (context, count) => Text('$count'),
)

// الأحداث
ElevatedButton(
  onPressed: () => context.read<CounterBloc>().add(Increment()),
  child: const Text('+1'),
)