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!

Cannot get the WebSockets example working

Answers

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