Mastering Middleware in NestJS: Elevate Your API’s Middleware Game

Middleware in NestJS plays a pivotal role in managing the request-response cycle, offering developers the chance to execute any code, make changes to request and response objects, end the request-response cycle, or even call the next middleware function in the stack. This article will deep-dive into the intricacies of middleware in NestJS, providing insights and best practices.

1. Understanding Middleware Purpose

Middleware functions are designed to perform tasks like:

• Logging
• Authentication and Authorization
• Parsing request bodies
• Handling CORS

While they seem simple, mastering their usage can profoundly enhance your application’s efficiency and security.

2. Implementing Basic Middleware

In NestJS, middleware is simply a class with an use() method.

import { Injectable, NestMiddleware } from '@nestjs/common';

@Injectable()
export class LoggerMiddleware implements NestMiddleware {
  use(req: Request, res: Response, next: Function) {
    console.log('Request was made to:', req.url);
    next();
  }
}