Advanced Angular Design Patterns — Factory, Facade, Proxy, and Dependency Injection

Continuing our exploration of Angular design pattern, this part focuses on Factory, Facade, proxy and Dependency injection- essential tools for creating scalable , efficient application.

Factory Pattern

Purpose: Creates objects without specifying their exact class.

Angular Use: Configurable services via useFactory.

Example

export function configFactory() {
  return new ConfigService({ apiEndpoint: 'https://api.example.com' });
}

@NgModule({
  providers: [{ provide: ConfigService, useFactory: configFactory }],
})
export class AppModule {}

Facade Pattern

Purpose: Provides a simplified interface to complex systems.

Angular Use: Centralized logic for managing state or services.

Example

@Injectable({ providedIn: 'root' })
export class UserFacade {
  constructor(private userService: UserService, private authService: AuthService) {}
  getUserDetails(userId: string) {
    return this.authService.isLoggedIn() ? this.userService.getUserById(userId) : throwError('Not logged in');
  }
}

Proxy Pattern