User presence in a socket.io 'room' - websocket

Question

I have a system where users connect to a 'room' using Socket.io. Right now, when people load a page, the connection is made, and I can see how many people are connected to the given page (the URL dictating the room).
What I want is to be able to see metadata about the users on the page. I want to somehow know that Bob, Steve and Mary are looking at the page. Right now I only get the internal session Ids.
Server
io.on('connection', function(socket) {
socket.on('viewPage', function(data, fn) {
var roomName = 'page-' + data.url;
socket.join(roomName);
var room = io.sockets.adapter.rooms[roomName];
console.log(Object.keys(room).length + ' users connected');
fn({msg: 'Connected to room ' + roomName})
})
});
Client
var socket = io();
socket = io.connect("http://localhost:5000");
socket.on('connect', function(data) {
socket.emit('viewPage', {url: '/foo/bar'}, function(resp) {
console.log(resp)
});
});
From looking at the Socket.io docs there's join and so on, but I don't see any way of attaching metadata to the client connection.
How would I go about doing this? How can I ensure that I can see a list of connected users on a page?

Answer 1

Here's a very simple and unsafe way of passing metadata from the client to the Server and attaching it to the sockets using middleware. Usually only a session id is passed and the data is fetched on the server but I've cut some corners.
//Client
socket = io.connect("http://localhost:5000", {query: 'name=Bob'});
//Server
io.use(function (socket, next){
var name = socket.handshake.query.name;
socket._name = name;
next();
});
Now you can do:
var room = io.sockets.adapter.rooms[roomName];
for (var key in room){
console.log(room[key]._name);
}
Note you should handle multi-tabbing from the same user so you'd need to display only distinct _name values