When building full-stack applications with Node.js, Express, and React, codebases often start simple but quickly turn into spaghetti code as features grow. Applying Clean Architecture principles guarantees separation of concerns, testability, and long-term maintainability.
1. Layered Controller-Service-Repository Pattern
Avoid writing database queries or business logic directly inside Express route controllers. Instead, decouple your backend into three clear layers:
- Controller Layer: Handles HTTP requests, extracts parameters, and returns response status codes.
- Service Layer: Contains business rules, validations, and orchestrates domain logic.
- Repository Layer: Handles direct database queries via Prisma or Mongoose models.
2. Centralized Error Handling
Never let unhandled promise rejections crash your application server. Implement custom error classes and centralized Express error middleware.