how can get the current session user information in nodejs on socket event?

First of all i'm rookie with nodejs, i started to learn it about 3-4 days and i read lots of articles but they made me more confuse!

var app = express();
var expressSession = require('express-session');
var cookieParser = require('cookie-parser');

app.use(cookieParser());

app.use(expressSession({
   key : 'session',
   secret: 'mySecretKey',
   store: sessionStore
}));

app.use(passport.initialize());
app.use(passport.session());

var server= require('http').Server(app) ;
var io = require('socket.io')(server);
var passportSocketIo = require("passport.socketio");

io.use(passportSocketIo.authorize({
  cookieParser: cookieParser,
  key:         'session',
  secret:      'mySecretKey',
  store:       sessionStore, 
  success:     onAuthorizeSuccess,
  fail:        onAuthorizeFail,
}));

It works great and check socket connection access, but there's a little big problem for me. How i can access the session id on socket messages? i want to search session data in my session store and find the current users information.

this piece of code seems not working:

io.on('connection',function(socket) {
   socket.on('myevent',function(){
    console.log("Session: ", socket.session);
   });
});