Cannot get the WebSockets example working

cfinis

Hello,
I'm running the LFW111 course examples on node 20.11.0 with

  "dependencies": {
    "@fastify/autoload": "^5.0.0",
    "@fastify/cors": "^9.0.1",
    "@fastify/sensible": "^5.0.0",
    "@fastify/websocket": "^10.0.1",
    "fastify": "^4.26.1",
    "fastify-cli": "^6.2.1",
    "fastify-plugin": "^4.0.0"
  },

The Web Sockets example in lesson 04 (Going Realtime) doesn't work for me. When I run the mock-service, and select a category in the static web page, the mock service of the routes/orders plugin throws an error complaining that the socket is undefined:

[16:45:38.506] ERROR (369197): Cannot read properties of undefined (reading 'send')
    reqId: "req-2"
    err: {
      "type": "TypeError",
      "message": "Cannot read properties of undefined (reading 'send')",
      "stack":
          TypeError: Cannot read properties of undefined (reading 'send')
              at Object.<anonymous> (file:///home/cfinis/workspace/jsnad/my-project-WS/mock-srv/routes/orders/index.mjs:9:16)
              at /home/cfinis/workspace/jsnad/my-project-WS/mock-srv/node_modules/@fastify/websocket/index.js:185:34
...
}

Any idea what is going wrong?

Thanks

dwloughran

I've got the same problem. Did you ever get it working?

jonatasmello

Hi,
here is what worked for me based on the official documentation

async ({ socket }, request) => {

use this instead:

async ( socket, request) => {

the parameter "socket" is just a variable, not an object (with {socket} )

Let's also create an index.mjs file in our newly created folder with the following contents:

"use strict";

export default async function (fastify, opts) {
  fastify.get(
    "/:category",
    { websocket: true },
    async (socket, request) => {
      socket.send(JSON.stringify({ id: "A1", total: 3 }));
    }
  )};

dwloughran

@jonatasmello , thank you! That was the problem.

kdhyne

Saved my sanity with this, thanks!

tonihoo

Thanks @jonatasmello. Could the admins fix this? Also, there is a minor bug on the related page https://trainingportal.linuxfoundation.org/learn/course/introduction-to-nodejs-lfw111x/going-real-time/real-time-functionality?page=4 -> the static files should be served with command npx serve -p 5050 static

abdulpathan1994

@jonatasmello Thanks it worked.

hedgehog1973

@jonatasmello said:
Hi,
here is what worked for me based on the official documentation

async ({ socket }, request) => {

use this instead:

async ( socket, request) => {

the parameter "socket" is just a variable, not an object (with {socket} )

Let's also create an index.mjs file in our newly created folder with the following contents:

"use strict";

export default async function (fastify, opts) {
  fastify.get(
    "/:category",
    { websocket: true },
    async (socket, request) => {
      socket.send(JSON.stringify({ id: "A1", total: 3 }));
    }
  )};

This is the miracle working code!! A crack!!

strdpl

Grazie!