redux_persist #

Persist Redux state across app restarts in Flutter.

Article.

Usage #

See example for a full overview.

The library creates a middleware that saves on every action. It also loads on initial load and sets a LoadAction to your store.

State Setup #

You will need to use a state class, with a required toJson method, as such:

class AppState {
  final int counter;

  AppState({this.counter = 0});

  AppState copyWith({int counter}) {
    return new AppState(counter: counter ?? this.counter);
  }

  // !!!
  static AppState fromJson(dynamic json) {
    return new AppState(counter: json["counter"]);
  }

  // !!!
  Map toJson() => {
    'counter': counter
  };
}

(the copyWith method is optional, but a great helper. The fromJson is required, but can be renamed)

Persistor #

Next, create your persistor and store, then load the last state in. This will usually be in your main or in your root widget:

persistor = new Persistor<AppState>(key: "my-app", decoder: AppState.fromJson);

store = new Store<AppState>(reducer,
    initialState: new AppState(),
    middleware: [persistor.createMiddleware()]);

persistor.load(store);

(the key param is used as a key of the save file name. The decoder param takes in a dynamic type and outputs an instance of your state class, see the above example)

Load #

In your reducer, you must add a check for the LoadAction action, like so:

class IncrementCounterAction {}

AppState reducer(state, action) {
  // !!!
  if (action is LoadAction<AppState>) {
    return action.state;
  }
  // !!!

  switch (action.runtimeType) {
    case IncrementCounterAction:
      return state.copyWith(counter: state.counter + 1);
    default:
      // No change
      return state;
  }
}

Persistor Gate #

If you want to wait until rendering you app until the state is loaded, use the PersistorGate:

@override
Widget build(BuildContext context) {
  return new PersistorGate(
    persistor: persistor,
    child: MyApp()
  );
}

If you want to display a loading screen (or slash screen), pass the Widget to render to the loading param of PersistorGate.

Features and bugs #

Please file feature requests and bugs at the issue tracker.