Nodejs How to export Socket IO in controller - node.js

Question

In Nodejs how to export socket IO in controller.
Socket.io Version - "socket.io": "^4.5.1",
Socket.js
let io = null;
// module.exports = {
// intialized_connection: (httpServer) => {
// return (io = require('socket.io')(httpServer, {
// cors: {
// origin: '*',
// methods: ['GET', 'POST', 'PUT', 'DELETE'],
// },
// }));
// },
// getIO: () => {
// if (!io) {
// throw new Error('Socket.io is not initialized');
// }
// return io;
// }
// }
class RealTime {
constructor() {
if (io) return io;
io = this;
return io;
}
intialized_connection(httpServer) {
return (io = require('socket.io')(httpServer, {
cors: {
origin: '*',
methods: ['GET', 'POST', 'PUT', 'DELETE'],
},
}));
}
init() {
io.on("connection", function (socket) {
console.log("A user connected", socket.id);
//Whenever someone disconnects this piece of code executed
// socket.on('custom-event', function(data) {
// console.log("Atique data: ", JSON.stringify(data));
// });
// socket.emit('custom-emit', "hello from nodejs")
socket.on('disconnect', function () {
console.log('A user disconnected');
});
});
}
getIO() {
if (!io) {
throw new Error('Socket.io is not initialized');
}
return io;
}
sendEvents(event, data) {
console.log("This.Socket:", this.socket);
return new Promise((resolve, reject) => {
this.getIO().emit(event, data, (response) => {
if (response.error) {
console.error(response.error);
reject(response.error);
} else {
resolve(true);
}
});
});
}
receivedEvents(event) {
console.log("Atique Ahmed Received Events ---->", event);
return new Promise((resolve, reject) => {
this.getIO().on(event, function(err, data) {
console.log("I am emiiting here, ")
if(err) {
reject(err);
}
resolve(data);
});
})
}
}
module.exports = {
RealTime
};
index.js
const express = require('express');
const bodyparser = require('body-parser');
const cors = require('cors');
const fileUpload = require('express-fileupload');
const http = require('http');
// const socketIO = require('./utils/socket');
const { RealTime } = require('./utils/socket');
const socket = new RealTime();
const app = express();
app.use(cors())
app.options('*', cors());
app.use(bodyparser.json({limit: '5mb', extended: true}))
app.use(bodyparser.urlencoded({limit: '5mb', extended: true}))
const authRoutes = require('./routes/authRoutes');
const apiRoutes = require('./routes/routes');
// For File Upload
app.use(fileUpload({
limits: { fileSize: 5 * 1024 * 1024 },
}));
app.use('/auth', authRoutes);
app.use('/user', apiRoutes);
//Capture All 404 errors
app.use(function (req,res,next){
res.status(404).send('Error - Unable to find the requested resource!');
});
app.use((req, res, next) => {
req.socket.on('error', () => {});
next();
});
const server = http.createServer(app);
socket.intialized_connection(server);
socket.init();
app.set('socketio', socket);//here you export my socket.io to a global
module.exports = server;
local.js
require('dotenv').config()
const server = require('./index');
const port = process.env.PORT || 8081;
const chalk = require('chalk');
// Server
server.listen(port, () => {
console.log(chalk.green('╔═══════════════════════════════════════════════════════════'));
console.log(chalk.green('║ Background Server Listening at | port: %s', port));
console.log(chalk.green('╚═══════════════════════════════════════════════════════════'));
});
Routes.js
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
app.use(bodyParser.json());
// Authentication
const authentication = require('../authentication');
// Middleware
const middleware = require('../middleware/headerValidation');
// Permission
const permissions = require('../permission/index')
// Controller
const userController = require('../controllers/userController');
const customerController = require('../controllers/customerController');
app.post('/submit-request', [middleware.bearerTokenPresent, authentication.verifyToken, permissions.fileUploadPermission], (req, res) => {
customerController.submitRequest(req, res);
});
module.exports = app;
customerController.js
exports.submitRequest = async(req, res) => {
const io = req.app.get('socketio');
io.emit('custom-emit', "Hello from nodejs");
io.on('custom-event', function(data) {
console.log("Atique:", JSON.stringify(data))
})
res.json("done")
}
Issue are -
The main issues are - socketio.on an socketio.emit is not working. It is working when I am putting everything, inside init method, I can't do that, I have to write the generic code, so it can be re-usable. -
init() {
io.on("connection", function (socket) {
console.log("A user connected", socket.id);
socket.on('custom-event', function(data) {
console.log("Atique data: ", JSON.stringify(data));
});
socket.emit('custom-emit', "hello from nodejs")
socket.on('disconnect', function () {
console.log('A user disconnected');
});
});
}
Frontend Angular 14, I am using, socket.io-client
Any idea, What I am doing wrong?

Answer 1

The object stored in your globals
app.set('socketio', socket);//here you export my socket.io to a global
is an instance of RealTime class and not of the require('socket.io').Server class.
please cache the reference to the proper object like so:
app.set('socketio',socket.intialized_connection(server));//here you export my socket.io to a global
socket.init();
change customerController.js:
exports.submitRequest = async (req, res) => {
const io = req.app.get('socketio');
///edited from io.on("connection", function (socket) {
io.once("connection", function (socket) {
socket.emit('custom-emit', "Hello from nodejs");
socket.on('custom-event', function (data) {
console.log("Atique:", JSON.stringify(data))
})
res.json("done")
});
}
you however have to keep in mind what listeners you are adding to the io object's "connection" or some other event as No checks are made to see if the listener has already been added. Multiple calls passing the same combination of "connection" and listener will result in the listener being added, and called, multiple times.
Consider using named functions and clearing the listener using removeListener() from time to time.
It is best to keep all your socket event listeners in one file for ease of debugging.
EDIT 1
index.js:
const server = http.createServer(app);
socket.intialized_connection(server);
socket.init();
app.set('socketio', socket);//here you export my socket.io to a global
make the following changes to your socket.js:
let io = null;
/// CHANGE:
let socketID = null;
class RealTime {
constructor() {
if (io) return io;
io = this;
return io;
}
intialized_connection(httpServer) {
return (io = require('socket.io')(httpServer, {
cors: {
origin: '*',
methods: ['GET', 'POST', 'PUT', 'DELETE'],
},
}));
}
init() {
io.on("connection", function (socket) {
console.log("A user connected", socket.id);
/// CHANGE:
socketID = socket.id
//Whenever someone disconnects this piece of code executed
// socket.on('custom-event', function(data) {
// console.log("Atique data: ", JSON.stringify(data));
// });
// socket.emit('custom-emit', "hello from nodejs")
socket.on('disconnect', function () {
console.log('A user disconnected');
});
});
}
/// CHANGE: getIO() {
getSocket() {
if (!io) {
throw new Error('Socket.io is not initialized');
}
return io.sockets.sockets.get(socketID);
}
.
.
.
.
for the receivedEvents and sendEvents to get reference to the socket.
Since you are caching the socket id here, this code will work only for one client properly.
change customerController.js:
exports.submitRequest = async (req, res) => {
const socket = req.app.get('socketio').getSocket();
socket.emit('custom-emit', "Hello from nodejs");
socket.on('custom-event', function (data) {
console.log("Atique:", JSON.stringify(data))
})
res.json("done")
}