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Hydrated provides a Subject that automatically persists to Flutter's local storage and hydrates on creation!

Easy to consume

All values are persisted with shared_preferences and restored with automatic hydration.

final count$ = HydratedSubject<int>("count", seedValue: 0);

/// count$ will automagically be hydrated with 42 next time it is created

Ready for BLoC

class HydratedBloc {
  final _count$ = HydratedSubject<int>("count", seedValue: 0);

  ValueObservable<int> get count$ => _count$.stream;
  Sink<int> get setCount => _count$.sink;

  dispose() {

Supports simple types and serialized classes

We support all shared_preferences types.

  • int
  • double
  • bool
  • String
  • List<String>
final count$ = HydratedSubject<int>("count");

We also support serialized classes with hydrate and persist arguments.

final user$ = HydratedSubject<User>(
  hydrate: (String s) => User.fromJson(s),
  persist: (User user) => user.toJson(),


Hydrated is mock tested with all supported types and is dogfooded by its creator.


Hydrated supports any key-value data storages -- just implement the KeyValueStore interface and you will be able to use hive, flutter_secure_storage or any other persistence solution of your choice.

class MyAwesomeKeyValueStore implements KeyValueStore {
  /// your implementation here...

final user = HydratedSubject<User>(
  hydrate: (String s) => User.fromJson(s),
  persist: (User user) => user.toJson(),
  keyValueStore: MyAwesomeKeyValueStore()


demo of Hydrated BehaviorSubject between app restarts

Original developer

hydrated was originally developed by @lukepighetti.