Unable to render user object to EJS view header.ejs - node.js

Question

I am new to EJS and Node.js. I have been struggling to send the user object data to ejs template page. Actually, I want to display the current user's name who logged into the portal.
This is some portion of app.js
app.use(function(req,res,next){
res.locals.success_msg=req.flash('success_msg');
res.locals.error_msg=req.flash('error_msg');
res.locals.not_registered_user_msg=req.flash('not_registered_user_msg');
res.locals.authdata = firebase.auth().currentUser;
next();
});
//Get user info
app.get('*',function(req,res,next){
if(firebase.auth().currentUser!=null){
var id = firebase.auth().currentUser.uid;
var profileRef = fbRef.child('users');
var query = profileRef.orderByChild('uid').equalTo(id);
query.once('value', function(snap){
var user = JSON.stringify(snap.val());
console.log('User data is: '+user);
res.locals.user = user;
});
}
next();
});
Here is the header.ejs where I want to retrieve and display current user's name:
I am able to enter into the if condition., and able to print the phrase "Welcome,". But unable to get the actual user data, it simply showing empty space like this
please suggest me, where did i gone wrong here! Thanks in advance.
As per sugegstion i am adding logs from console here. I am getting user data from firebase including child id as marked here.

Answer 1

This doesn't look right to me:
var user = JSON.stringify(snap.val());
console.log('User data is: '+user);
res.locals.user = user;
You're converting the user object into a JSON string. Try this instead:
var user = snap.val();
console.log('User data is: ' + JSON.stringify(user));
res.locals.user = user;
I'm not really familiar with Firebase but I'd also guess that once is asynchronous, so you'd need to wait before calling next, a bit like this:
if (firebase.auth().currentUser != null) {
// ... This bit the same as before ...
query.once('value', function(snap) {
var user = snap.val();
console.log('User data is: ' + JSON.stringify(user));
res.locals.user = user;
next();
});
}
else {
next();
}
If that still doesn't work, could you include the output of the console logging in your question?

Answer 2

From reading over the express documentation, it seems that the arguments passed into the request handler are req and res.
You do not get the next function as an argument. With that said, you need to change your app.get to an app.use which is where you get the actual next function.
app.use((req, res, next) => {
if (firebase.auth().currentUser) {
const { uid } = firebase.auth().currentUser
const profileRef = fbRef.child('users')
const query = profileRef.orderByChild('uid').equalTo(uid);
query.once('value', snap => {
const user = JSON.stringify(snap.val())
res.locals.user = user
})
}
next()
})