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@wingkit-leung
Last active January 9, 2023 10:05
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Flutter cross platform data persistence solution: shared_preferences with riverpod
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:shared_preferences/shared_preferences.dart';
// A Counter example implemented with riverpod and shared_preferences
/// Providers are declared globally and specify how to create a state
final counterProvider = StateProvider((ref) => 0);
final sharedPrefs = Provider<SharedPreferences>((ref) {
throw UnimplementedError();
});
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
final sharedPreferences = await SharedPreferences.getInstance();
runApp(
// Adding ProviderScope enables Riverpod for the entire project
ProviderScope(overrides: [
sharedPrefs.overrideWithValue(sharedPreferences),
], child: const MyApp()),
);
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return const MaterialApp(home: Home());
}
}
class Home extends ConsumerWidget {
const Home({Key? key}) : super(key: key);
@override
Widget build(BuildContext context, WidgetRef ref) {
return Scaffold(
appBar: AppBar(title: const Text('Flutter101')),
body: Center(
child: Consumer(builder: (context, ref, _) {
final count = ref.watch(counterProvider.state).state;
final prefs = ref.read(sharedPrefs);
final countPref = prefs.getInt('counter') ?? 0;
if (count != countPref) {
Future.delayed(Duration.zero).then(
(value) => ref.read(counterProvider.state).state = countPref);
}
return Text(
'$countPref',
style:
DefaultTextStyle.of(context).style.apply(fontSizeFactor: 5.0),
);
}),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
final prefs = ref.read(sharedPrefs);
final countPref = (prefs.getInt('counter') ?? 0) + 1;
prefs.setInt('counter', countPref);
ref.read(counterProvider.state).state = countPref;
},
child: const Icon(Icons.add),
),
);
}
}
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