Multiple parameters in @SubscribeMessage functions

I’m submitting a…

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

Current behavior

It seems that there is no support for socket adapters that pass multiple parameters to the message handler functions. This becomes an issue when trying to use acknowledgement functions in socket.io for example.

According to #249 this should be possible to do with a custom socket adapter, but I can’t get it to work. Somewhere along the way to the message handler the second parameter is dropped.

Expected behavior

I would like to be able to do something like this: socket.emit('event', 'some data', function (response) { /*do something*/ }); and then the socket adapter should pass both the data and the function into the message handler function:

@SubscribeMessage('event')
onStart(client, data, ack) {
  //Do stuff
  ack('stuff completed');
}

I also posted about this here, but no one seems to have a working solution.

Environment

Nest version: 4.6.6

 
For Tooling issues:
- Node version: 8.10.0  
- Platform:  Mac

[josiahdahl]

@BorntraegerMarc Here’s a solution that works for me - not sure if it’s what you need as my experience with websockets is limited.

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

  @SubscribeMessage('event')
  onEvent(client, [data, cb]) {
    cb('Custom Data');
  }
}

// Assuming a socket.io instance socket
const socket = io('http://localhost:3001');
// ....
socket.emit('event', 'Some data', (res) => {
  console.log(res);
  // Logs: Custom Data
});

I have a minimal example here https://github.com/josiahdahl/nestjs-ws-callback-example. Clone it, yarn install, yarn run start, then visit localhost:3000 and open your console to see the callback being handled.

[AndyGura]

I wrote this module over nestjs, which do it under the hood so you don’t need to call ack callback explicitly, you only need to return value or throw error: https://www.npmjs.com/package/nestjs-socket-handlers-with-ack . Hope it helps