Middleware trong NestJS — functional vs class middleware, apply theo routes?

Middleware thực thi trước Guards, có access vào raw req/res/next giống Express. Dùng cho logging, CORS, session, body parsing, request tracking.

Functional middleware là function đơn giản (req, res, next) => { next() } — dùng khi không cần DI. Class middleware implement NestMiddleware với method use(req, res, next) và @Injectable() — dùng khi cần inject services.

Apply middleware trong module implements NestModule với configure(consumer: MiddlewareConsumer). consumer.apply(Middleware).forRoutes('*') apply cho tất cả. .forRoutes({ path: 'users', method: RequestMethod.GET }) hoặc .forRoutes(UsersController) cho specific routes/controllers. .exclude() loại trừ routes cụ thể. Có thể chain nhiều middleware: .apply(M1, M2, M3). Global middleware (Express-style) dùng app.use(helmet(), cors(), express.json()) trong main.ts trước khi listen.

Middleware executes before Guards and has access to raw req/res/next like Express. Used for logging, CORS, session, body parsing, and request tracking.

Functional middleware is a simple function (req, res, next) => { next() } — use when DI is not needed. Class middleware implements NestMiddleware with a use(req, res, next) method and @Injectable() — use when services need to be injected.

Apply middleware in a module implements NestModule with configure(consumer: MiddlewareConsumer). consumer.apply(Middleware).forRoutes('*') applies to all. .forRoutes({ path: 'users', method: RequestMethod.GET }) or .forRoutes(UsersController) targets specific routes/controllers. .exclude() exempts certain routes. Chain multiple middleware: .apply(M1, M2, M3). Global middleware (Express-style) uses app.use(helmet(), cors(), express.json()) in main.ts before listening.