How to pass data received through Mongoose to the template?

Question

Mongoose

Good afternoon. If I get data from the database and display it on the page like this, then everything is output normally:

var selectedUser = User.findOne({'_id': '5991bf82b9a87a624407907e'}, (err, user) => {
    console.log('result', err, user);
    res.render("userpage.hbs", {
        username: user.username 
    });
});

But what if I need to move the data outside the return function? Because this code no longer works, and I need to display the data exactly like this:

var selectedUser = User.findOne({'_id': '5991bf82b9a87a624407907e'}, (err, user) => {
    console.log('result', err, user);
});

res.render("userpage.hbs", {
    username: user.username
});

Answer 1

var selectedUser = User.findOne({'_id': '5991bf82b9a87a624407907e'}, (err, user) => {
    console.log('result', err, user);
    someFunction(user);
});

function someFunction (user) {
    res.render("userpage.hbs", {
        username: user.username
    });
}

Answer 2

The 'user' variable is in a different scope, so the second option will not work in this form.
The easiest fix is ​​to create a variable that is global to these two function calls and write everything you need into it. And then read the value in the render function