Lernen Repository Pattern | App Architecture

The Repository Pattern is a design pattern that helps you separate data access logic from the business logic in your application. By introducing a repository, you create an abstraction layer between the data sources (such as APIs, databases, or local storage) and the parts of your code that use this data. This decoupling allows your application to remain flexible and maintainable, as changes to data sources or how data is fetched do not directly impact the business logic. In Flutter and Dart, the Repository Pattern is commonly used to ensure that your app's core functionality is not tightly coupled to a specific data source, making it easier to test, maintain, and extend.

main.dart


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abstract class UserRepository {
  Future<String> fetchUserName();
}

class MockUserRepository implements UserRepository {
  @override
  Future<String> fetchUserName() async {
    // Simulate fetching data from a mock data source
    await Future.delayed(Duration(seconds: 1));
    return 'Alice Example';
  }
}

void main() async {
  UserRepository repository = MockUserRepository();
  String userName = await repository.fetchUserName();
  print('Fetched user name: $userName');
}

With the Repository Pattern, you can easily swap out one data source for another without changing the business logic that depends on the repository. For instance, the UserRepository interface defines the contract for fetching a user name, while MockUserRepository provides a mock implementation. If you later decide to fetch user data from a remote API or a local database, you can create a new class that implements UserRepository and provide that implementation instead. This approach keeps your codebase flexible and adaptable, as you only need to change the repository implementation rather than refactor your entire app whenever the data source changes.

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main.dart


              123456789101112131415161718
            
abstract class UserRepository {
  Future<String> fetchUserName();
}

class MockUserRepository implements UserRepository {
  @override
  Future<String> fetchUserName() async {
    // Simulate fetching data from a mock data source
    await Future.delayed(Duration(seconds: 1));
    return 'Alice Example';
  }
}

void main() async {
  UserRepository repository = MockUserRepository();
  String userName = await repository.fetchUserName();
  print('Fetched user name: $userName');
}

War alles klar?

Danke für Ihr Feedback!

Abschnitt 1. Kapitel 2