Express Skill
Express backend for Luxia e-commerce uses a service layer pattern with modular routing. Routes handle HTTP concerns, services contain business logic, and middleware manages cross-cutting concerns like auth and rate limiting.
Quick Start
Creating a Route
typescript
// backend/src/routes/exampleRoutes.ts
import { Router } from 'express';
import { body, validationResult } from 'express-validator';
import { authenticate } from '../middleware/authMiddleware';
import { exampleService } from '../services/exampleService';
const router = Router();
router.post(
'/',
authenticate,
[body('name').notEmpty(), body('email').isEmail()],
async (req, res) => {
const errors = validationResult(req);
if (!errors.isEmpty()) {
return res.status(400).json({ errors: errors.array() });
}
try {
const result = await exampleService.create(req.body);
res.status(201).json(result);
} catch (error: any) {
console.error('Error:', error);
res.status(500).json({ message: error.message });
}
}
);
export default router;
Creating a Service
typescript
// backend/src/services/exampleService.ts
import { pool } from '../db/client';
export const exampleService = {
async create(payload: { name: string; email: string }) {
const result = await pool.query(
'INSERT INTO examples (name, email) VALUES ($1, $2) RETURNING *',
[payload.name, payload.email]
);
return result.rows[0];
},
async findById(id: number) {
const result = await pool.query(
'SELECT * FROM examples WHERE id = $1',
[id]
);
return result.rows[0] || null;
}
};
Key Concepts
| Concept | Usage | Example |
|---|---|---|
| Route | HTTP endpoint definition | router.get('/items', handler) |
| Service | Business logic encapsulation | itemService.findById(id) |
| Middleware | Request preprocessing | authenticate, rateLimiter |
| Validator | Input validation | body('email').isEmail() |
| Pool | Database connection | pool.query(sql, params) |
Common Patterns
Protected Admin Route
typescript
router.use(authenticate); // All routes below require auth
router.get('/', async (req, res) => {
const adminId = (req as AuthenticatedRequest).adminId;
// ...
});
Optional Authentication
typescript
router.get('/public', optionalAuth, async (req, res) => {
const userId = (req as AuthenticatedRequest).userId; // May be undefined
// ...
});
File Upload with Processing
typescript
router.post('/', authenticate, upload.single('image'), async (req, res) => {
if (!req.file) {
return res.status(400).json({ message: 'No file provided' });
}
const processed = await sharp(req.file.buffer).webp().toBuffer();
// ...
});
See Also
- •routes - Route organization and patterns
- •services - Service layer architecture
- •database - PostgreSQL query patterns
- •auth - JWT authentication flow
- •errors - Error handling patterns
Related Skills
- •See the postgresql skill for database schema and query optimization
- •See the typescript skill for type safety patterns
- •See the node skill for Node.js runtime patterns
- •See the zod skill for runtime validation (alternative to express-validator)