Cannot get the WebSockets example working

cfinis · June 2024

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 · August 2024

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

jonatasmello · August 2024

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 · August 2024

@jonatasmello , thank you! That was the problem.

kdhyne · September 2024

Saved my sanity with this, thanks!

tonihoo · September 2024

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 · October 2024

@jonatasmello Thanks it worked.

hedgehog1973 · October 2024

@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 · October 2024

Grazie!

lmcamara · February 1

Muchas gracias. Funciona correctamente con los datos originales, pero en cuanto añades nuevos registros estos quedan permanentemente sin definir. Entiendo que es lo normal dado que es un simple ejemplo.

Cannot get the WebSockets example working

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