hydrated_riverpod

---

Overview

hydrated_riverpod extension to the riverpod state management library which automatically persists and restores riverpod states.

Like hydrated_bloc

hydrated_riverpod 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 hive for a platform-agnostic, performant storage layer.

Usage

Setup HydratedRiverpod

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final storage = HydratedStorage.build(storageDirectory: ...)
  HydratedRiverpod.initialize(storage: storage);
  runApp(ProviderScope(child: MyApp()));
}

Create a HydratedStateNotifier

class Counter extends HydratedStateNotifier<int> {
  Counter() : super(0);

  void increment() => state++;

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

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

Now the Counter will automatically persist/restore their state. We can increment the counter value, hot restart, kill the app, etc... and the previous state will be retained.

HydratedMixin

class Counter extends StateNotifier<int> with HydratedMixin {
  CounterCubit() : super(0) {
    hydrate();
  }

  void increment() => state++;

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

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

Custom Storage Directory

Any storageDirectory can be used when creating an instance of HydratedStorage:

final 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 HydratedRiverpod 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

  HydratedRiverpod.initialize(storage: MyHydratedStorage());
  runApp(ProviderScope(child: MyApp()));

Dart Versions

• Dart 2: >= 2.12