hydrated_state_notifier

Description:

hydrated state notifier

Hydrated State Notifier #








Features #
An extension to the state_notifier
library which automatically persists and restores states using HydratedStorage. A hive implementation of HydratedStorage is hydrated_state_notifier_hive.
Usage #
Setup HydratedStorage #
Install
Add package to your project with
dart pub add hydrated_state_notifier hydrated_state_notifier_hive
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Import package
Add below lines in your dart file
import 'package:hydrated_state_notifier/hydrated_state_notifier.dart';
import 'package:hydrated_state_notifier_hive/hydrated_state_notifier_hive.dart';
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Initialize
void main() async {
WidgetsFlutterBinding.ensureInitialized();

/// Initialize the common storage by providing [HiveHydratedStorage].
/// You can also provide your own implementation of [HydratedStorage].
HydratedStorage.storage = await HiveHydratedStorage.build(
storageDirectory: kIsWeb
? ''
: await getTemporaryDirectory(),
);

runApp(App())
}
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Create a HydratedStateNotifier #
Does automatic state persistence for the [StateNotifier] class.
class CounterController extends HydratedStateNotifier<int> {
CounterController() : super(0);

void increment() => state = state + 1;

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

@override
Map<String, int> toJson(int state) => { 'value': state };
}
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Now the CounterController 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.
It uses the same cache for the same type. Use the id parameter if you intend
to have different cache for different intance of same type.
class CounterController extends HydratedStateNotifier<int> {
CounterController(String id) : super(0, id: id);

void increment() => state = state + 1;

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

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

CounterController('first_counter');
CounterController('second_counter');
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Create a HydratedStateController #
A subclass of [HydratedStateNotifier] for simple scenarios.
final counterController = HydratedStateController(
0,
fromJson: (json) => json['count'] as int,
toJson: (state) => {'count': state},
);
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Now the counterController 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.
It uses the same cache for the same type. Use the id parameter if you intend
to have different cache for different intance of same type.
final counterController = HydratedStateController(
0,
fromJson: (json) => json['count'] as int,
toJson: (state) => {'count': state},
id: 'counter_1',
);
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final counterController = HydratedStateController(
0,
fromJson: (json) => json['count'] as int,
toJson: (state) => {'count': state},
id: 'counter_2',
);
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HydratedMixin #
class CounterController extends StateNotifier<int> with HydratedMixin {
CounterController() : super(0) {
// Hydrate must be called if using HydratedMixin or implementing any
// [HydratedStateNotifier], or [HydratedStateController].
hydrate();
}

void increment() => state = state + 1;

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

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

@override
String get id => '';

@override
// Use a common storage or pass another
HydratedStorage get storage => HydratedStorage.storage;

@override
// Will be used for writing migrations in a later version
int get version => 1;
}
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HydratedStorage #
You can implement a custom Storage by simply implementing the HydratedStorage interface and initializing HydratedStateNotifier with the custom Storage.
// my_hydrated_storage.dart

class MyHydratedStorage implements HydratedStorage {
@override
Object? read(String key) {
// TODO: implement read
}

@override
Future<void> write(String key, Object? value) async {
// TODO: implement write
}

@override
Future<void> delete(String key) async {
// TODO: implement delete
}

@override
Future<void> clear() async {
// TODO: implement clear
}
}
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Setting a common storage for all.
// main.dart

HydratedBloc.storage = MyHydratedStorage();
runApp(MyApp());
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or providing storage through the parameters:
final counterController = HydratedStateController(
0,
fromJson: (json) => json['count'] as int,
toJson: (state) => {'count': state},
storage: MyHydratedStorage(),
);

// or

class CounterController extends HydratedStateNotifier<int> {
CounterController(String id) : super(0, id: id, storage: MyHydratedStorage());

void increment() => state = state + 1;

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

@override
Map<String, int> toJson(int state) => { 'value': state };
}
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Additional information #
This is based on hydrated_bloc, and
hydrated_notifier.