How to pass changes from middleware to socket.io? - node.js

Question

I am using node.js with socket.io to push real time notifications to users. However, currently I am just sending back a query result done in my socket.io code and sending it back to the client but I need to let socket know about the changes that occur and to either update with the changes or re-query the db to check for the new number and send that to the client.
For example if a user gets a friend request then the notification count will change and I want socket.io to push the new notification count number to the user.
here is my socket.io code in my app.js file:
io.on('connection', function(socket) {
var sessionID = socket.handshake.sessionID,
session = new connect.middleware.session.Session({ sessionStore: sessionStore }, socket.handshake.session)
console.log('socket: new ' + sessionID)
socket.broadcast.emit('arpNewConn', session.passport.user)
var intervalID = setInterval(function() {
socket.handshake.session.reload(function() {
socket.handshake.session.touch().save()
})
socket.emit('pulse', { heartbeat: new Date().toString(), timestamp: new Date().getTime() })
}, 300 * 1000)
socket.on('disconnect', function() {
console.log('socket: dump ' + sessionID)
socket.broadcast.emit('arpLostConn', session.passport.user)
clearInterval(intervalID)
})
socket.emit('entrance', {message: 'Message works'});
dbnotif.findOne(userID, function (err, user) {
if(err) throw err;
notify = user.notifications;
socket.emit('notify', {notific: notify});
});
});
Here is the client side:
div#CheckSocket
script(src='http://localhost:3000/socket.io/socket.io.js')
script.
$(document).ready(function () {
console.log('socket');
var socket = io.connect('http://localhost:3000/');
console.log('entered1');
socket.on('entrance', function (data) {
console.log('entered');
console.log(data.message);
});
socket.on('notify', function (data) {
console.log('noting');
console.log(data.notific);
if(data.notific !== 0)
$('.notifications').html(data.notific);
});
socket.on('reconnecting', function(data) {
setStatus('reconnecting');
console.log('entered2');
});
function setStatus(msg) {
console.log('connection status: ' + msg);
console.log('entered5');
}
});
Here is the example of adding a friend in the route file:
exports.addContactPost = function(req, res, err) {
async.waterfall([
function(callback) {
var success;
var newFriend = new Friend ({
userId: req.signedCookies.userid,
friend_id: mongoose.Types.ObjectId(req.body.otherUser),
friend_status: 1
});
newFriend.save(function(err){
if(err) {
console.log(err);
} else {
console.log("saved it");
success = true;
}
});
callback(null, success)
},
function(success, callback) {
//if(success === true) {
var success2;
var newFriend2 = new Friend ({
userId: mongoose.Types.ObjectId(req.body.otherUser),
friend_id: req.signedCookies.userid,
friend_status: 2
});
newFriend2.save(function(err){
if(err) {
res.send("request not received");
} else {
success2 = true;
}
});
callback(null, success2);
//} else {
// res.send("error with request sent");
//}
},
function(success2, callback) {
console.log('callback3');
//if(success2 === true) {
var success3;
Notification.findOneAndUpdate({userId: mongoose.Types.ObjectId(req.body.otherUser)}, {
$inc: {notifications: 1}
}, function(err, notify) {
if(err) {
res.send(err);
} else {
console.log(notify);
if(notify.added_notifications === true) {
// enable mail and include general u have got a new request... do not include name because not storing it
}
}
success3 = true;
callback(null, success3);
}],
function(err, results) {
res.json({response: true});
console.log("Add successful");
});
};
Notes: dbnotif is a model being called by mongoose,
userID is a global variable available to the file

Answer 1

I helped him solve this question offline, but we ended up using an EventEmitter as a proxy.
// main.js
var EventEmitter = require('events').EventEmitter;
var emitter = new EventEmitter();
Then add it to each request as middleware:
// elsewhere in main.js
app.use(function(req, res, next) {
req.emitter = emitter;
next();
});
Then in external routes file:
// routes.js
exports.addContactPost = function(req, res, err) {
req.emitter.emit( 'some-key', whatever, data, you, want );
};