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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.

demo of Hydrated tests completing successfully


demo of Hydrated BehaviorSubject between app restarts


The goal of Hydrated is to make persistence of BLoC classes as simple as possible for Flutter projects. PRs are welcome, but be warned that I am committed to simplicity.