hydrated_bloc 8.1.0

An extension to the bloc state management library which automatically persists and restores bloc states.

example/lib/main.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_services_binding/flutter_services_binding.dart';
import 'package:hydrated_bloc/hydrated_bloc.dart';
import 'package:path_provider/path_provider.dart';

void main() async {
  FlutterServicesBinding.ensureInitialized();
  final storage = await HydratedStorage.build(
    storageDirectory: kIsWeb
        ? HydratedStorage.webStorageDirectory
        : await getTemporaryDirectory(),
  );
  HydratedBlocOverrides.runZoned(
    () => runApp(App()),
    storage: storage,
  );
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider(
      create: (_) => BrightnessCubit(),
      child: AppView(),
    );
  }
}

class AppView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocBuilder<BrightnessCubit, Brightness>(
      builder: (context, brightness) {
        return MaterialApp(
          theme: ThemeData(brightness: brightness),
          home: CounterPage(),
        );
      },
    );
  }
}

class CounterPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocProvider<CounterBloc>(
      create: (_) => CounterBloc(),
      child: CounterView(),
    );
  }
}

class CounterView extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final textTheme = Theme.of(context).textTheme;
    return Scaffold(
      appBar: AppBar(title: const Text('Counter')),
      body: Center(
        child: BlocBuilder<CounterBloc, int>(
          builder: (context, state) {
            return Text('$state', style: textTheme.headline2);
          },
        ),
      ),
      floatingActionButton: Column(
        crossAxisAlignment: CrossAxisAlignment.end,
        mainAxisAlignment: MainAxisAlignment.end,
        children: <Widget>[
          FloatingActionButton(
            child: const Icon(Icons.brightness_6),
            onPressed: () => context.read<BrightnessCubit>().toggleBrightness(),
          ),
          const SizedBox(height: 4),
          FloatingActionButton(
            child: const Icon(Icons.add),
            onPressed: () {
              context.read<CounterBloc>().add(CounterIncrementPressed());
            },
          ),
          const SizedBox(height: 4),
          FloatingActionButton(
            child: const Icon(Icons.remove),
            onPressed: () {
              context.read<CounterBloc>().add(CounterDecrementPressed());
            },
          ),
          const SizedBox(height: 4),
          FloatingActionButton(
            child: const Icon(Icons.delete_forever),
            onPressed: () {
              HydratedBlocOverrides.current?.storage.clear();
            },
          ),
        ],
      ),
    );
  }
}

abstract class CounterEvent {}

class CounterIncrementPressed extends CounterEvent {}

class CounterDecrementPressed extends CounterEvent {}

class CounterBloc extends HydratedBloc<CounterEvent, int> {
  CounterBloc() : super(0) {
    on<CounterIncrementPressed>((event, emit) => emit(state + 1));
    on<CounterDecrementPressed>((event, emit) => emit(state - 1));
  }

  @override
  int fromJson(Map<String, dynamic> json) => json['value'] as int;

  @override
  Map<String, int> toJson(int state) => {'value': state};
}

class BrightnessCubit extends HydratedCubit<Brightness> {
  BrightnessCubit() : super(Brightness.light);

  void toggleBrightness() {
    emit(state == Brightness.light ? Brightness.dark : Brightness.light);
  }

  @override
  Brightness fromJson(Map<String, dynamic> json) {
    return Brightness.values[json['brightness'] as int];
  }

  @override
  Map<String, dynamic> toJson(Brightness state) {
    return <String, int>{'brightness': state.index};
  }
}