What is middleware?

• Middleware is a function that is called before the route handler (controller)
• Middleware in NestJs is a way to intercept and handle incoming requests before they reach the route handlers. It allows you to perform actions such as authentication, validation, logging, and error handling at a global or local level in your application.

Type of middleware

• Module-based

• Global Middleware

Method of creating middleware

• Function-based
• Class-Based

Function-based

function globalMiddlewareOne(req:Request,res:Response,next:NextFunction){
  console.log("This is global middleware one")
  next()
}

Class-Based

@Injectable()
export class BookMiddleware implements NestMiddleware {
  use(req: Request, res: Response, next: NextFunction) {
    let protocol = req.protocol; //http https
    let host = req.get('host'); //localhost
    let url = req.originalUrl;
    let method = req.method;
    let date = new Date().toDateString();

    console.log(
      protocol + '://' + host + url + '   ' + method + '  ' + date,
    );
    next();
  }
}