I did the wrong implementation of socket.io. I am trying to implement a lengthy poll based on mysql data.
For this demo, I get user data for each user connected to the long poll server that I created. Each user passes their unique user_id to the server to receive data associated with it. (In a real application I want to receive user notifications)
Users connect to the server, and the server also does a long poll from the database. But the problem is that the same data is returned to the client, although I am missing unique identifiers from the client side.
User 1 passed identifier 5, and user 2 passed identifier 3. Both of these users receive the same data as a response (user 1 data)
Here's the client code :
var user_id = 5; //hardcoded for now, but in real its fetched from a form var params = { userId: user_id, }; // create a new websocket var socket = io.connect('http://localhost:8000', { query: params }); // on message received we print all the data inside the
Here is the server side code:
var app = require('http').createServer(handler), io = require('socket.io').listen(app), fs = require('fs'), mysql = require('mysql'), connectionsArray = [], connection = mysql.createConnection({ host: 'localhost', user: 'root', password: '', database: 'dumydb', port: 3306 }), POLLING_INTERVAL = 5000, pollingTimer; // If there is an error connecting to the database connection.connect(function (err) { // connected! (unless `err` is set) if (err) { console.log(err); } }); // creating the server ( localhost:8000 ) app.listen(8000); // on server started we can load our client.html page function handler(req, res) { fs.readFile(__dirname + '/client.html', function (err, data) { if (err) { console.log(err); res.writeHead(500); return res.end('Error loading client.html'); } res.writeHead(200); res.end(data); }); } // creating a new websocket to keep the content updated without any AJAX request io.sockets.on('connection', function (socket) { var userId = socket.handshake.query.userId; // starting the loop only if at least there is one user connected if (!connectionsArray.length) { pollingLoop(userId); } socket.on('disconnect', function () { var socketIndex = connectionsArray.indexOf(socket); console.log('socketID = %s got disconnected', socketIndex); if (~socketIndex) { connectionsArray.splice(socketIndex, 1); } }); console.log('A new socket is connected!'); connectionsArray.push(socket); }); var pollingLoop = function (userId) { var params = [userId]; // Doing the database query var tempQuery = `SELECT full_name FROM users WHERE id=?`; var query = connection.query(tempQuery, params), users = []; // this array will contain the result of our db query // setting the query listeners query .on('error', function (err) { // Handle error, and 'end' event will be emitted after this as well updateSockets(err); }) .on('result', function (user) { // it fills our array looping on each user row inside the db users.push(user); }) .on('end', function () { // loop on itself only if there are sockets still connected if (connectionsArray.length) { pollingTimer = setTimeout(function () { pollingLoop(userId) }, POLLING_INTERVAL); updateSockets({ users: users }); } else { console.log('The server timer was stopped because there are no more socket connections on the app') } }); }; var updateSockets = function (data) { // adding the time of the last update data.time = new Date(); // sending new data to all the sockets connected connectionsArray.forEach(function (tmpSocket) { tmpSocket.volatile.emit('notification', data); }); }; console.log('Please use your browser to navigate to http://localhost:8000');
This is the guide I'm following: Link
Can someone help me understand why the same data is passed to all users? Thanks!
UPDATE 1
I tried the solutions provided by Theo and Abdul Slave Memon. My updateSockets () were changed, but now the data is only clicked on the first connected client. I did console.log () Take a look at this:
UPDATE 2 : package.json
{ "name": "nodejs-MySQL-push-notifications-demo", "version": "1.0.0", "description": "nodejs-MySQL-push-notifications-demo", "main": "server.js", "dependencies": { "express": "^4.16.2", "mysql": "~2.5.4", "socket.io": "~1.3.2" }, "devDependencies": {}, "scripts": { "test": "echo \"Error: no test specified\" && exit 1", "start": "node server.js" }, "repository": { "type": "git", "url": "git://github.com/GianlucaGuarini/nodejs-MySQL-push-notifications-demo.git" }, "author": "Gianluca Guarini", "license": "BSD-2-Clause", "bugs": { "url": "https://github.com/GianlucaGuarini/nodejs-MySQL-push-notifications-demo/issues" }, "homepage": "https://github.com/GianlucaGuarini/nodejs-MySQL-push-notifications-demo" }