Configuring Express 4.0 routes with socket.io

Question

I have created a new Express application. It generated app.js for me and I have then created the following index.js bringing in socket.io:

var app = require('./app');
server=app.listen(3000);

var io = require('socket.io');
var socket = io.listen(server, { log: false });

socket.on('connection', function (client){
    console.log('socket connected!');
});

Can anyone advise how I would access socket.io within the routes files?

For reference, the default generated app.js is below:

var express = require('express');
var path = require('path');
var favicon = require('static-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');

var routes = require('./routes/index');
var users = require('./routes/users');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(favicon());
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded());
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', routes);
app.use('/users', users);

/// catch 404 and forwarding to error handler
app.use(function(req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

/// error handlers

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
    app.use(function(err, req, res, next) {
        res.status(err.status || 500);
        res.render('error', {
            message: err.message,
            error: err
        });
    });
}

// production error handler
// no stacktraces leaked to user
app.use(function(err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});


module.exports = app;

Answer 1

SocketIO does not work with routes it works with sockets.

That said you might want to use express-io instead as this specially made for this or if you are building a realtime web app then try using sailsjs which already has socketIO integrated to it.

Do this to your main app.js

app = require('express.io')()
app.http().io()

app.listen(7076)

Then on your routes do something like:

app.get('/', function(req, res) {
    // Do normal req and res here
    // Forward to realtime route
    req.io.route('hello')
})

// This realtime route will handle the realtime request
app.io.route('hello', function(req) {
    req.io.broadcast('hello visitor');
})

See the express-io documentation here.

Or you can do this if you really want to stick with express + socketio

On your app.js

server = http.createServer(app)
io = require('socket.io').listen(server)
require('.sockets')(io);

Then create a file sockets.js

module.exports = function(io) {

    io.sockets.on('connection', function (socket) {
        socket.on('captain', function(data) {
            console.log(data);
            socket.emit('Hello');
        });
    });
};

You can then call that to your routes/controllers.

Answer 2

The route:

const Router = require('express').Router

const router = new Router();

router.get('/my-route', (req, res, next) => {
    console.log(req.app.locals.io) //io object
    const io = req.app.locals.io
    io.emit('my event', { my: 'data' }) //emit to everyone
    res.send("OK")
});

module.exports = router

The main file:

const app = require('express')()
const server = require('http').Server(app);
const io = require('socket.io')(server)
const myroute = require("./route") //route file dir

app.use(myroute);

server.listen(3000, () => {
    console.log('¡Usando el puerto 3000!');
});

app.locals.io = io

Answer 3

I think a better way to do it is to attach the Io server to response object In the first middleware .per the way express is designed the Io server will be available to your subsequent routes.

Check this link