Clean Architecture in Flutter

Why Clean Architecture?

As Flutter projects grow, maintaining code quality becomes challenging. Clean Architecture provides a clear separation of concerns that makes your codebase testable and maintainable.

The Layers

Presentation Layer

Widgets and UI logic. Receives data from the domain layer and displays it.

Domain Layer

Business logic and entities. Independent of any framework or external dependency.

Data Layer

Repositories, data sources, and API calls. Implements the interfaces defined in the domain layer.

Key Principles

1. Dependency Rule: Dependencies point inward. Domain knows nothing about Presentation.
2. Separation of Concerns: Each layer has a single responsibility.
3. Testability: Business logic can be tested without UI or infrastructure.

Implementation Example

// Domain layer
abstract class UserRepository {
  Future<User> getUser(String id);
}

// Data layer
class ApiUserRepository implements UserRepository {
  @override
  Future<User> getUser(String id) async {
    final response = await http.get(Uri.parse('/users/$id'));
    return User.fromJson(jsonDecode(response.body));
  }
}

Conclusion

Clean Architecture takes time to set up but pays dividends as your project scales.