?? Flutter Architecture Patterns You Need to Know

After building multiple production Flutter apps, I've discovered some architectural patterns that significantly improve code maintainability and scalability. Here's what you should know!

1. The Repository Pattern Done Right

// Instead of scattered API calls:
class UserService {
  Future<User> fetchUser() async {
    final response = await http.get('/api/user');
    return User.fromJson(response.data);
  }
  
  // Repository Pattern:
  abstract class UserRepository {
    Future<User> getUser();
    Future<void> updateUser(User user);
  }
  
  class UserRepositoryImpl implements UserRepository {
    final ApiClient _client;
    final LocalStorage _storage;
    
    @override
    Future<User> getUser() async {
      try {
        final user = await _client.fetchUser();
        await _storage.cacheUser(user);
        return user;
      } catch (e) {
        return _storage.getCachedUser();
      }
    }
  }
}
        

2. Smart Service Locator

// Easy dependency injection
final getIt = GetIt.instance;

void setupLocator() {
  getIt.registerLazySingleton<UserRepository>(
    () => UserRepositoryImpl(
      getIt<ApiClient>(),
      getIt<LocalStorage>(),
    ),
  );
}

// Usage anywhere:
final userRepo = getIt<UserRepository>();
        

3. Reactive State Management Pattern

class UserState extends StateNotifier<AsyncValue<User>> {
  final UserRepository _repository;
  
  UserState(this._repository) : super(const AsyncValue.loading()) {
    loadUser();
  }
  
  Future<void> loadUser() async {
    state = const AsyncValue.loading();
    try {
      final user = await _repository.getUser();
      state = AsyncValue.data(user);
    } catch (e) {
      state = AsyncValue.error(e);
    }
  }
}        

?? Pro Tips:

1. Always separate business logic from UI
2. Use immutable state objects
3. Implement proper error handling at repository level
4. Cache network responses strategically
5. Use dependency injection for better testing

?? Question for the community: What architecture patterns have you found most effective in your Flutter projects?

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