delay between my function and the redirection to a route

I'm working on a page in nodeJs with express which return me a table. I have an error about my variable "allMusique" containing my data on my page when I try to access it but after I reload once, the page shows up correctly with my data. Does someone see what is wrong please?

Here is my code:

var express = require('express');
var router = express.Router();
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/";
var allMusique;
var idMaxMusique;
router.get(‘/’, function(req, res, next) {

function getAllMusique(){

MongoClient.connect(url, function(err, db) {

if (err) throw err;

var dbo = db.db(“projet_node”);

dbo.collection(“musiques”).find({}).toArray(function(err, result) {

if (err) throw err;

allMusique = result;

var size = allMusique.length-1;

idMaxMusique = parseInt(result[size].id)+1;

});

});

}
getAllMusique();
res.render('musiques', { resultat: allMusique, idMax: idMaxMusique });

});
module.exports = router;

#javascript #node-js #express