Nest: @WebSocketServer() server -> server is null

Created on 31 Oct 2018 · 6Comments · Source: nestjs/nest

I'm submitting a...


[ ] Regression 
[x] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

Gateway @WebSocketServer() server example is returning "null", then i can't emit messages for client

Expected behavior

I created the native socket io variable, but this variable is null and doesn't works

Minimal reproduction of the problem with instructions

import {
SubscribeMessage,
WebSocketGateway,
WebSocketServer,
WsResponse,
} from '@nestjs/websockets';
import { from, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@WebSocketGateway()

export class EventsGateway {
@WebSocketServer() server;

constructor() {
this.server.emit('testing', { do: 'stuff' });
}

@SubscribeMessage('testing')
sendTesting(client, data) {
client.emit('testing', { testing: 'works' });
}
}

What is the motivation / use case for changing the behavior?

Environment


Nest version: 5.1.0


For Tooling issues:
- Node version:  8.9.0
- Platform:  Windows

Others:

Source

Root-Control

Most helpful comment

The @WebSocketServer() property will be assigned after init, not in the constructor

I think it should look something like this (not tested):

import {
SubscribeMessage,
WebSocketGateway,
WebSocketServer,
WsResponse,
OnGatewayInit,
} from '@nestjs/websockets';
import { from, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@WebSocketGateway()
export class EventsGateway implements OnGatewayInit {
  @WebSocketServer() server;

  afterInit() {
    this.server.emit('testing', { do: 'stuff' });
  }

  @SubscribeMessage('testing')
  sendTesting(client, data) {
    client.emit('testing', { testing: 'works' });
  }
}

More information in the docs under Server chapter

BrunnerLivio on 31 Oct 2018

👍3

All 6 comments

The @WebSocketServer() property will be assigned after init, not in the constructor

I think it should look something like this (not tested):

import {
SubscribeMessage,
WebSocketGateway,
WebSocketServer,
WsResponse,
OnGatewayInit,
} from '@nestjs/websockets';
import { from, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@WebSocketGateway()
export class EventsGateway implements OnGatewayInit {
  @WebSocketServer() server;

  afterInit() {
    this.server.emit('testing', { do: 'stuff' });
  }

  @SubscribeMessage('testing')
  sendTesting(client, data) {
    client.emit('testing', { testing: 'works' });
  }
}

More information in the docs under Server chapter

BrunnerLivio on 31 Oct 2018

👍3

The @WebSocketServer() property will be assigned after init, not in the constructor

I think it should look something like this (not tested):

import {
SubscribeMessage,
WebSocketGateway,
WebSocketServer,
WsResponse,
OnGatewayInit,
} from '@nestjs/websockets';
import { from, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@WebSocketGateway()

export class EventsGateway implements OnGatewayInit {
@WebSocketServer() server;

afterInit() {
this.server.emit('testing', { do: 'stuff' });
}

@SubscribeMessage('testing')
sendTesting(client, data) {
client.emit('testing', { testing: 'works' });
}
}

More information in the docs under Server chapter

Works, server now is not null, but strangely afterInit is not emiting data to ui.

  afterInit() {
    console.log(this.server);
    this.server.emit('testing', { do: 'stuff' });
  }

Root-Control on 31 Oct 2018

@Root-Control
I do not think this is directly related to Nest anymore. Maybe try to debug your client by creating a minimal socket-io client listener similar to this one, so you can debug where the problem is.

BrunnerLivio on 31 Oct 2018

Thanks @BrunnerLivio for helping with this issue. The second part is not related to Nest itself.

kamilmysliwiec on 31 Oct 2018

I know this is closed but I also had a problem where server was null well after app boot. In my case I had left App.component.ts with the default content, i.e. it was listening on the top level route / and I assume blocking any websocket listeners from instantiating, on any port.

As above ,in the emit I am also not getting any data through, just the event name.