redux_persist 0.0.2

Persist Redux State

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.