An extension to the bloc state management library which automatically persists and restores bloc states and is built on top of hydrated_cubit.
Overview
hydrated_bloc exports a Storage interface which means it can work with any storage provider. Out of the box, it comes with its own implementation: HydratedStorage.
HydratedStorage is built on top of path_provider for a platform-agnostic storage layer. The out-of-the-box storage implementation reads/writes to file using the toJson/fromJson methods on HydratedBloc and should perform very well for most use-cases (performance reports coming soon). HydratedStorage is supported for desktop (example).
Usage
1. Use HydratedStorage
void main() async {
WidgetsFlutterBinding.ensureInitialized();
HydratedBloc.storage = await HydratedStorage.build();
runApp(App());
}2. Extend HydratedBloc and override fromJson/toJson
enum CounterEvent { increment, decrement }
class CounterBloc extends HydratedBloc<CounterEvent, int> {
CounterBloc() : super(0);
@override
Stream<int> mapEventToState(CounterEvent event) async* {
switch (event) {
case CounterEvent.decrement:
yield state - 1;
break;
case CounterEvent.increment:
yield state + 1;
break;
}
}
@override
int fromJson(Map<String, dynamic> json) => json['value'] as int;
@override
Map<String, int> toJson(int state) => { 'value': state };
}Now our CounterBloc is a HydratedBloc and will automatically persist its state. We can increment the counter value, hot restart, kill the app, etc... and our CounterBloc will always retain its state.
Custom Storage Directory
By default, all data is written to temporary storage which means it can be wiped by the operating system at any point in time.
An optional storageDirectory can be provided to override the default temporary storage directory:
HydratedBloc.storage = await HydratedStorage.build(
storageDirectory: await getApplicationDocumentsDirectory(),
);Custom Hydrated Storage
If the default HydratedStorage doesn't meet your needs, you can always implement a custom Storage by simply implementing the Storage interface and initializing HydratedBloc with the custom Storage.
// my_hydrated_storage.dart
class MyHydratedStorage implements Storage {
@override
dynamic read(String key) {
// TODO: implement read
}
@override
Future<void> write(String key, dynamic value) async {
// TODO: implement write
}
@override
Future<void> delete(String key) async {
// TODO: implement delete
}
@override
Future<void> clear() async {
// TODO: implement clear
}
}// main.dart
HydratedBloc.storage = MyHydratedStorage();Maintainers
Supporters
Starware
Hydrated Bloc is Starware.
This means you're free to use the project, as long as you star its GitHub repository.
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