Get user data in RoleGuard with passport JWT authentication

I've managed to get JWT authentication in my nestJS application. Now I want to implement the role guard and have therefore to check the role of the authenticated user. Therefore, I thought of requesting the respective user role from the database. But this call is async and this is not doable within the guard.

My question is: How can I get the user role information within the Guard? I could put the information in the JWT token, but this seems not right to me, or am I wrong?

Here, Implementing Passport JWT you can put your findUser in the validate function that is async. And then create a decorator to return the user Auth JWT in decorator in NESTJS

So you need to do some things like this

//jwt.strategy.ts
import { ExtractJwt, Strategy } from 'passport-jwt';
import { PassportStrategy } from '@nestjs/passport';
import { Injectable } from '@nestjs/common';
import { jwtConstants } from './constants';

@Injectable()
export class JwtStrategy extends PassportStrategy(Strategy) {
  constructor() {
    super({
      jwtFromRequest: ExtractJwt.fromAuthHeaderAsBearerToken(),
      ignoreExpiration: false,
      secretOrKey: jwtConstants.secret,
    });
  }

  async validate(payload: any) {
    // Your JWT payload
    // Insert here the findOne from you're BDD
    return { userId: payload.sub, username: payload.username };
  }
}

And then

//user.decorator.ts
import { createParamDecorator, ExecutionContext } from '@nestjs/common';

export const User = createParamDecorator((data: any, ctx: ExecutionContext) => {
  const request = ctx.switchToHttp().getRequest();
  return request.user;
});

And in your controller juste use

//user.controller.ts
import { User } from './user.decorator';

@Get()
async getUser(@User() user) {
  //console.log(user);
}