How can we access decorator from a service class in NestJS - authorization

Question

I am new in NestJS and trying to do auth system. I was able to do. So here is what I am doing to get access to auth.
In my controller I have
#Get('/user')
async getUser(#AuthUser() token: string) : Promise<Object> {
return this.authService.getUser(token)
return token
}
Here I am passing a AuthUser decorator I want to avoid passing in controllers.
In the authService.getUser method I have something like this
async getUser(token: string): Promise<Object> {
try {
const user = await this.jwtService.verifyAsync(token)
return user
} catch (error) {
return false
}
}
and my decorator looks like this
import { createParamDecorator, ExecutionContext } from '#nestjs/common';
export const AuthUser = createParamDecorator(
(data = 'u_ses', ctx: ExecutionContext) => {
const request = ctx.switchToHttp().getRequest();
return data ? request.cookies?.[data] : request.cookies;
},
);
I don't like code. If I need to know the user id from a service class or anywhere I would need to pass the token and to get token I need use #AuthUser() token: string)
So I want to do something like this
this.authService.getUser(), here I don't want to pass token or anything and should be able to access this getUser method from anywhere. Since it's a service class, I can inject and use it but I won't have the token.
I tried injecting the decorator inside the service class, but this doesn't work.
One best solution I would prefer is to use the JWT things inside the decorator, so I don't need the service class' method :)
I am looking for a nicer solutions from you :)
Thank you.

Answer 1

Nestjs has NestMiddleware. Here, you can authorize before access to controller like this:
import { Injectable, NestMiddleware, UnauthorizedException } from '#nestjs/common';
import { Request, Response, NextFunction } from 'express';
#Injectable()
export class AuthenticationMiddleware implements NestMiddleware {
use(req: Request, res: Response, next: NextFunction) {
const headerAuthentication = req.headers.authorization;
if(!headerAuthentication) throw new UnauthorizedException('Authorization failed!');
const token = req.headers.authorization.split(' ')[1];
if(token) {
next();
}else {
throw new UnauthorizedException('Authorization failed!');
}
}
}
and in AppModule implement it
configure(consumer: MiddlewareConsumer) {
consumer.apply(AuthenticationMiddleware).forRoutes('/');
}
}