Clean Architecture

ELI5 — The Vibe Check

Clean Architecture is like an onion with strict rules: the inner layers (your core business logic) have absolutely no idea the outer layers (databases, APIs, UI) even exist. This means you can swap your database from Postgres to MongoDB and your business logic doesn't care at all.

Real Talk

Clean Architecture (by Robert C. Martin) organizes code into concentric layers: Entities (enterprise business rules), Use Cases (application business rules), Interface Adapters, and Frameworks/Drivers. The Dependency Rule states all dependencies must point inward — inner layers know nothing about outer layers.

Show Me The Code

// Use Case (inner layer - no framework deps)
class CreateUserUseCase {
  constructor(private userRepository: IUserRepository) {}
  async execute(data: CreateUserDTO): Promise<User> {
    const user = new User(data);
    return this.userRepository.save(user);
  }
}

When You'll Hear This

"Clean Architecture makes our business logic framework-agnostic." / "The use cases layer shouldn't import from Express."