Riverpod AsyncNotifier

1
import 'package:riverpod_annotation/riverpod_annotation.dart';
2
 
3
part 'user_provider.g.dart';
4
 
5
@riverpod
6
class UserNotifier extends _$UserNotifier {
7
  @override
8
  Future<User> build(String userId) async {
9
    return _fetchUser(userId);
10
  }
11
 
12
  Future<void> refresh() async {
13
    state = const AsyncLoading();
14
    state = await AsyncValue.guard(() => _fetchUser(ref.read(userIdProvider)));
15
  }
16
 
17
  Future<void> updateName(String newName) async {
18
    final current = state.valueOrNull;
19
    if (current == null) return;
20
 
21
    state = const AsyncLoading();
22
    state = await AsyncValue.guard(() async {
23
      final updated = await ref.read(userRepositoryProvider).updateName(current.id, newName);
24
      return updated;
25
    });
26
  }
27
 
28
  Future<User> _fetchUser(String id) {
29
    return ref.read(userRepositoryProvider).getUser(id);
30
  }
31
}
32
 
33
// Simple provider
34
@riverpod
35
Future<List<Post>> userPosts(Ref ref, String userId) async {
36
  final user = await ref.watch(userNotifierProvider(userId).future);
37
  return ref.read(postRepositoryProvider).getPostsByUser(user.id);
38
}
39
 
40
// Usage
41
class UserPage extends ConsumerWidget {
42
  const UserPage({super.key, required this.userId});
43
  final String userId;
44
 
45
  @override
46
  Widget build(BuildContext context, WidgetRef ref) {
47
    final userAsync = ref.watch(userNotifierProvider(userId));
48
    return userAsync.when(
49
      data: (user) => Text(user.name),
50
      loading: () => const CircularProgressIndicator(),
51
      error: (err, _) => Text('Error: $err'),
52
    );
53
  }
54
}