Inject provider in decorator function

Question

Basically, I need to pass an authService to the "verifyClient" function inside the @WebSocketGateway decorator, like so :

@WebSocketGateway({
  transports: ['websocket'],
  verifyClient: (info: { req: IncomingMessage }, done: (result: boolean, code: number, msg?: string) => void) => {
    try {
      const keys = authService.verify(//stuff); //how do I inject this service ?
      //more stuff
      done(true, 200);
    } catch (error) {
      done(false, 401, 'invalid token');
      return;
    }
  }
})
export class WsGateway implements OnGatewayConnection, OnGatewayDisconnect {...

I tried doing someting like that :

function verifyClient(info: { req: IncomingMessage }, done: (result: boolean, code: number, msg?: string) => void) {
  try {
    const injectAuthService = Inject(AuthService);
    injectAuthService(this,'authService');
    const auth: AuthService = this.authService; 
    const keys = auth.verify(//stuff) 
    //more stuff
    done(true, 200);
  } catch (error) {
    done(false, 401, 'invalid token');
    return;
  }
}

@WebSocketGateway({
  transports: ['websocket'],
  verifyClient: verifyClient
})
export class WsGateway implements OnGatewayConnection, OnGatewayDisconnect {...

based on this and this but it doesn't work, this.authService is undefined

it's not so clear what are you trying to achieve, do you want that your class will have the `AuthService`? do you want the custom function you wrote will be executed? will be available somewhere? BTW the `verifyClient` property is not something that NestJS is familiar with by default — Hagai Kalinhoff, Feb 01 '22 at 16:18

score 0 · Answer 1 · answered Aug 18 '22 at 19:33

I faced a similar issue, but at the end, I just used the jsonwebtoken library,which is what is used under the hood by @nest/jwtService, assuming you want to verify the token as well. I couldn't find any other way to do it.

import * as jwt from 'jsonwebtoken';

import * as queryString from 'query-string';
import { AuthService } from '../authentication/auth.service';

export function verifyClient(info, cb) {
  const [_path, params] = info.req.url?.split('?') as string[];
  const token = queryString.parse(params).token;
  if (!token) {
    cb(false, 401, 'Unauthorized');
  } else {
    try {
      (info.req as any).userId = (jwt.decode(token as string) as any).id;
      cb(true);
    } catch (err) {
      console.log(err);
      cb(false, 401, 'Unauthorized');
    }
  }
}

@WebSocketGateway({
  cors: {
    origin: '*',
    methods: ['GET', 'POST'],
    credentials: true,
  },
  verifyClient,
})
export class UserWebSocketGateway implements OnGatewayInit

Inject provider in decorator function

1 Answers1