Problem with findOne() in sequelize node.js - node.js

Question

I have a problem with node.js and sequelize findOne(). I want to find new students, that I want to add to the DB (var novi), and the ones that already exist, I just want to update their field (var stari). Everything works as expected, only when I want to return JSON with how many new students I added to the DB, and how many are updated, values of stari and novi, go back to 0, but the counting is good, I checked. I know the problem is with asynchronous call, but I don't know how to fix.
app.post('/student', function(req,res) {
var imeGodine = req.body['godina'];
//POMOĆNE SKRIPTE BitBucket.js i citanjeGodina.js
var broj = 0;
var stari = 0;
var novi = 0;
db.godina.findOne({where:{nazivGod:req.body.godina}}).then(god => {
var studenti = req.body.studenti;
db.student.count().then (ranijeStudenata => {
for(var i = 0; i<studenti.length; i++) {
var ime = studenti[i].imePrezime;
var ind = studenti[i].index;
db.student.findOne({where:{index :studenti[i].index}}).then(stud => {
if (stud == null) {
novi++;
db.student.create({imePrezime:ime, index : ind}).then(noviStudent => {
god.addStudenti(noviStudent);
});
}
else if (stud != null) {
stari++;
god.addStudenti(stud);
}
});
broj++;
}
var brojNovih = broj - ranijeStudenata; //ne koristi se, ali možda hoće
res.set("Content-Type", "application/json");
res.status(200).send(JSON.stringify({message: "Dodano je " + novi + " novih studenata i upisano " + stari + " na godinu " + imeGodine}));
});
});
});
Picture of code

Answer 1

You can use async/await to do counting in a synchronous way.
'use strict';
app.post('/student', async function (req, res) {
var imeGodine = req.body['godina'];
var {studenti} = req.body;
var broj = 0;
var stari = 0;
var novi = 0;
let god = await db.godina.findOne({where: {nazivGod: req.body.godina}});
let ranijeStudenata = await db.student.count(); // ranijeStudenata not used?
for (var i = 0; i < studenti.length; i++) {
var ime = studenti[i].imePrezime;
var ind = studenti[i].index;
let stud = await db.student.findOne({where: {index: studenti[i].index}});
if (stud === null) {
novi++;
let noviStudent = await db.student.create({imePrezime: ime, index: ind});
god.addStudenti(noviStudent);
} else if (stud !== null) {
stari++;
god.addStudenti(stud);
}
broj++;
}
return res.status(200).send({
message: "Dodano je " + novi + " novih studenata i upisano " + stari + " na godinu " + imeGodine
});
});