Lesson 9 / 33

Middleware

Intercept and process requests before they reach controllers.

Write middleware

Middleware is a function or class that runs before/after a route handler.

import { Injectable, NestMiddleware } from '@nestjs/common';
import { Request, Response, NextFunction } from 'express';

@Injectable()
export class LoggerMiddleware implements NestMiddleware {
  use(req: Request, res: Response, next: NextFunction) {
    console.log(`${req.method} ${req.path}`);
    next();
  }
}

Apply middleware

Apply in configure() method of a module, specifying routes to intercept.

export class AppModule implements NestModule {
  configure(consumer: MiddlewareConsumer) {
    consumer
      .apply(LoggerMiddleware)
      .forRoutes('users'); // or use { path: 'users', method: RequestMethod.GET }
  }
}