Cannot get session data from middleware in node.js - node.js

Question

I have a function that gets the id of the user when she registers
user.save(function(err, id){
if(err) return next(err);
req.session.uid=id;
})
Then, I wrote this middleware
var User = require('../user');//contains the code above
module.exports = function(req,res,next){
var uid = req.session.uid;
if(!uid) return next();//if not logged in
else{//else is logged in
User.get(uid, function(err, user){
//get user object and pass it to locals
if (err) console.log("error from midd > "+err);
req.user = res.locals.user = user;
next();
})
}
}
I define my middleware in the app.js like so
var user = require('./lib/middleware/user');
app.use(session({resave:'false', saveUninitialized:'false', secret:'secret'}));
app.use(user); //<-- my middleware
app.use(express.static(path.join(__dirname, 'public')));
app.set('multimedia', __dirname + '/public/multimedia');
app.use(messages);
app.get('/register', register.form);
app.post('/register', register.submitit);
Then I check if there is an id in the locals and show the right menu, by using ejs
<%if (locals.user) {%>
<div id='menu'>
<a href='/post'>post</a>
<a href='/logout'>logout</a>
</div>
<%}else{ %>
<div id='menu'>
<a href='/login'>login</a>
<a href='/register'>sign up</a>
</div>
<%}%>
This never works. In every page, even if I am registered, I never see the menu for the registered users (post and logout).
I put many console.log all over the code and looks like the middleware never gets the session.uid.
console.log("req.session.uid = "+req.session.uid); inside the middleware always gives undefined, even though saving the user works and returns an id that I pass to session req.session.uid=id;
How do I fix this? Please advise because I am stuck.
Thanks

Answer 1

Note: I cannot be sure this is your error because you didn't paste the code around user.save(). But I'm enoughly confident that is the cause.
Session.Save(): This method is automatically called at the end of the HTTP response if the session data has been altered (though this behavior can be altered with various options in the middleware constructor). Because of this, typically this method does not need to be called.
As I can see here:
user.save(function(err, id){
if(err) return next(err);
req.session.uid=id;
})
You either:
Fail to save the new user and continue the process with next(err) (which end the HTTP response)
Or succeed and probably get stuck (<= not enough code shown to know what...)
In case of success you should probably call next() or next(null).
Because of that, the altered session (ie: req.session.uid=id;) is never saved. Thus, resulting in a failure of retrieving the uid in the middleware.