Nestjs Roles Decorator: Crazy behaviour with getting user out of payload data

Question

I am just trying to implement my Roles Decorator in Nestjs. So far it went pretty well, until I wanted to compare the user of the payload data from the jwt-token to the required role. I can't explain how this is possible, but it is only possible to get the user and role out of the payload data, if i let the function return always true. After I set a condition the user is undefined. How is this even possible?

Here is my (shortened) user controller, where I use the Decorator:

    @UseGuards(JwtAuthGuard, RolesGuard)
@Controller('users')
export class UsersController {
  constructor(private readonly userService: UserService) {}
  private readonly logger = new Logger(LoggingService.name);

  @Post('/create')
  async create(@Body() createUserDto: CreateUserDto) {
    const hashedPassword = await bcrypt.hash(createUserDto.password, 10);
    createUserDto.password = hashedPassword
    return this.userService.createUser(createUserDto);
  }

  @Roles(Role.SUPERADMIN)
  @Get('/')
  showUsers() {
    return this.userService.getUsers();
  }

And here is the roles decorator, with condition:

import { CanActivate, ExecutionContext, Injectable, Logger } from '@nestjs/common';
import { Reflector } from '@nestjs/core';
import { Observable } from 'rxjs';
import { LoggingService } from 'src/services/logging/logging.service';
import { User } from 'src/user/schemas/user.schema';
import { Role } from '../role.enum';
import { ROLES_KEY } from '../decorators/roles.decorator';
import { Types } from 'mongoose';

@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private readonly reflector: Reflector) {}
  private readonly logger = new Logger(LoggingService.name);

    canActivate(context: ExecutionContext): boolean | Promise<boolean> | Observable<boolean> {

        const roles = this.reflector.get<Role[]>(ROLES_KEY, context.getHandler());
        // If there is no Roles-Decorator, just pass through
        if (!roles) {
          return true;
        }

        this.logger.debug("REQUIRED ROLES: ", roles)
        

        const request = context.switchToHttp().getRequest();
        const userRole = request.user?.roles;
        const userID = request.user?.sub;
        this.logger.debug("ROLES GUARD USER", userID);
        this.logger.debug("USER ROLE", userRole);


        // Else, check the request header if it matches

        if (roles.includes(userRole)) {
            return true;
        } else { return false }

  }

}

Logging output (when I try to access the route):

[Nest] 4460  - 25.11.2021, 18:56:33   DEBUG [LoggingService] REQUIRED ROLES: 
[Nest] 4460  - 25.11.2021, 18:56:33   DEBUG [LoggingService] superadmin
[Nest] 4460  - 25.11.2021, 18:56:33   DEBUG [LoggingService] ROLES GUARD USER
[Nest] 4460  - 25.11.2021, 18:56:33   DEBUG [LoggingService] undefined
[Nest] 4460  - 25.11.2021, 18:56:33   DEBUG [LoggingService] USER ROLE
[Nest] 4460  - 25.11.2021, 18:56:33   DEBUG [LoggingService] undefined

But when I do this:

// Else, check the request header if it matches

        // if (roles.includes(userRole)) {
        //     return true;
        // } else { return false }

        return true;

The logging output is this:

[Nest] 39888  - 25.11.2021, 19:00:14   DEBUG [LoggingService] REQUIRED ROLES: 
[Nest] 39888  - 25.11.2021, 19:00:14   DEBUG [LoggingService] superadmin
[Nest] 39888  - 25.11.2021, 19:00:14   DEBUG [LoggingService] ROLES GUARD USER
[Nest] 39888  - 25.11.2021, 19:00:14   DEBUG [LoggingService] 619962ad86e412dc06983a0e
[Nest] 39888  - 25.11.2021, 19:00:14   DEBUG [LoggingService] USER ROLE
[Nest] 39888  - 25.11.2021, 19:00:14   DEBUG [LoggingService] superadmin

The control-flow is top to bottom, right? Any help would be greatly appreciated!

Answer 1

Using APP_GUARD in any module that is registered by the application registers the guard as a global guard, that will run before every request. What I would do is register two global guards, one for the JwtAuthGuard one for the RolesGuard, and implement a @JwtSkip() decorator, that tells the JwtAuthGuard that it can skip authentication on this route (would be the same for the RolesGuard as it shouldn't have any roles associated with it