How to pass reflector to Nest.js global guard?

I am new to nest.js and I have a question. I have a Roles Guard like this

import { CanActivate, ExecutionContext, Injectable } from '@nestjs/common';
import { Observable } from 'rxjs';
import { Reflector } from '@nestjs/core';

@Injectable()
export class RolesGuard implements CanActivate {
  constructor(private readonly reflector: Reflector) {
  }

  canActivate(context: ExecutionContext): boolean | Promise<boolean> | Observable<boolean> {
    const roles = this.reflector.get<string[]>('roles', context.getHandler());
    if (!roles) {
      return true;
    }
    const request = context.switchToHttp().getRequest();
    const user = request.user;
    return user.role.some(role => !!roles.find(item => item === role));
  }

}

Now I want to use this guard as a global guard like this

app.useGlobalGuards(new RolesGuard())

But it says that I need to pass argument(the reflector) to the guard as I mentioned in the constructor, now will it be okay to initialize the reflector like this?

const reflector:Reflector = new Reflector();
app.useGlobalGuards(new RolesGuard(reflector))

Or is there a better way to do this?

Solution

On the official Nest JS fundamentals course, in lecture "54 Protect Routes with Guards", the instructor specifies it is not best practice to create instance of reflector yourself.

A better way to resolve dependencies is to create a common module, and register your guard there. That way, reflector instance is resolved by nest runtime and you can also specify imports array for any other dependencies.

import { Module } from '@nestjs/common';
import { APP_GUARD } from '@nestjs/core';
import { AuthTokenGuard } from './guards/auth-token.guard';
import { ConfigModule } from '@nestjs/config';

@Module({
  imports: [ConfigModule],
  providers: [
    {
      provide: APP_GUARD,
      useClass: AuthTokenGuard,
    },
  ],
})
export class CommonModule {}