backend-dev-guidelines

Backend Development Guidelines

Layered Architecture

Request Flow:
Client → Routes → Controllers → Services → Repositories → Database

src/
├── routes/           # Route definitions
├── controllers/      # Request handling
├── services/         # Business logic
├── repositories/     # Data access
├── middleware/       # Express middleware
├── validators/       # Input validation
├── types/           # TypeScript types
├── utils/           # Utilities
└── config/          # Configuration

Layer Responsibilities

Routes Layer

• Define endpoints
• Apply middleware
• Route to controllers

// routes/users.routes.ts
import { Router } from 'express';
import { UserController } from '../controllers/user.controller';
import { validateRequest } from '../middleware/validate';
import { createUserSchema, updateUserSchema } from '../validators/user.validator';

const router = Router();
const controller = new UserController();

router.get('/', controller.getAll);
router.get('/:id', controller.getById);
router.post('/', validateRequest(createUserSchema), controller.create);
router.put('/:id', validateRequest(updateUserSchema), controller.update);
router.delete('/:id', controller.delete);

export default router;

Controllers Layer

• Handle HTTP request/response
• Extract and validate input
• Call services
• Return responses

// controllers/user.controller.ts
import { Request, Response, NextFunction } from 'express';
import { UserService } from '../services/user.service';

export class UserController {
  private userService = new UserService();

  getAll = async (req: Request, res: Response, next: NextFunction) => {
    try {
      const users = await this.userService.findAll();
      res.json({ data: users });
    } catch (error) {
      next(error);
    }
  };

  getById = async (req: Request, res: Response, next: NextFunction) => {
    try {
      const { id } = req.params;
      const user = await this.userService.findById(id);
      
      if (!user) {
        return res.status(404).json({ error: 'User not found' });
      }
      
      res.json({ data: user });
    } catch (error) {
      next(error);
    }
  };

  create = async (req: Request, res: Response, next: NextFunction) => {
    try {
      const user = await this.userService.create(req.body);
      res.status(201).json({ data: user });
    } catch (error) {
      next(error);
    }
  };
}