Riverpod Patterns

Best practices and common patterns for using Fasq with Riverpod to build maintainable and performant applications.

Provider Organization

Organize providers by feature or domain. Instead of .family, use functions to pass parameters:


// user_providers.dart
 
final usersProvider = queryProvider<List<User>>(
  'users'.toQueryKey(),
  () => api.fetchUsers(),
);
 
final userProvider = (String userId) => queryProvider<User>(
  ['user', userId].toQueryKey(),
  () => api.fetchUser(userId),
);
 
final createUserProvider = mutationProvider<User, Map<String, dynamic>>(
  (data) => api.createUser(data),
);
 
final updateUserProvider = (String userId) => mutationProvider<User, Map<String, dynamic>>(
  (data) => api.updateUser(userId, data),
);

State Management Patterns

Derived State

Create computed state from query results using Riverpod’s Provider:


final activeUsersProvider = Provider<List<User>>((ref) {
  // Watch the query provider
  final users = ref.watch(usersProvider).value ?? [];
 
  // Return derived data
  return users.where((user) => user.isActive).toList();
});
 
final userCountProvider = Provider<int>((ref) {
  return ref.watch(usersProvider).value?.length ?? 0;
});

Side Effects & Mutations

Global Error Handling

Use a dedicated provider or utility for consistent error feedback:


final createUserProvider = mutationProvider<User, String>(
  (name) => api.createUser(name),
  options: MutationOptions(
    onError: (error, name) {
      // Access global notification service or context
      showGlobalError('Failed to create user "$name": $error');
    },
  ),
);
 
// In your widget:
ElevatedButton(
  onPressed: () => ref.read(createUserProvider.notifier).mutate('John Doe'),
  child: Text('Create'),
)

Cache Invalidation Strategies

Centralize cache invalidation after mutations to keep your UI in sync:


final updateUserProvider = (String userId) => mutationProvider<User, String>(
  (newName) => api.updateUser(userId, newName),
  options: MutationOptions(
    onSuccess: (user, newName) {
      // 1. Invalidate specific user query
      ref.invalidate(userProvider(userId));
 
      // 2. Invalidate users list
      ref.invalidate(usersProvider);
 
      // 3. Optional: manually update cache for instant feedback
      // ref.read(fasqClientProvider).setQueryData(['user', userId].toQueryKey(), user);
    },
  ),
);

Form Handling

Integrate mutations with form state:


class UserForm extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final mutation = ref.watch(createUserProvider);
    final nameController = useTextEditingController();
 
    return Column(
      children: [
        TextField(controller: nameController),
 
        ElevatedButton(
          // Disable button while loading
          onPressed: mutation.isLoading
            ? null
            : () => ref.read(createUserProvider.notifier).mutate(nameController.text),
          child: mutation.isLoading
            ? CircularProgressIndicator()
            : Text('Submit'),
        ),
 
        if (mutation.hasError)
          Text('Error: ${mutation.error}', style: TextStyle(color: Colors.red)),
      ],
    );
  }
}

Repository Pattern

For complex apps, wrap your API calls in a repository and inject it using Riverpod:


final userRepositoryProvider = Provider((ref) => UserRepository(api: api));
 
final usersProvider = queryProvider<List<User>>(
  'users'.toQueryKey(),
  () {
    final repo = ref.watch(userRepositoryProvider);
    return repo.getAllUsers();
  },
);

Performance Tips

Watch Granularly: Use .select if you only need a specific property of the data to avoid unnecessary rebuilds.
Handle Loading Gracefully: Use AsyncValue.when to ensure users see a loading state while data is being fetched.
Background Sync: Mention that AsyncValue holds previous data during background refetching (stale-while-revalidate), making the app feel faster.
Dispose Unused Queries: queryProvider uses AutoDispose by default, so it cleans up after itself when the last widget stops watching.

Next Steps

queryProvider - Standard data fetching
mutationProvider - Handling server-side updates
Examples - Full application examples