Code executes before i get the response from the database - node.js

Question

I am new to Express and writing the code to get the list from my database. I'm trying to update the quantity of the items in my list. Now there can be multiple items and quantity for those items needs to be updated accordingly. The problem I am facing is when I try to get the list and update item accordingly, before my for loop executes to update the item it doesn't update the item's quantity in the database and saves the order. What am I doing wrong?
I have used async functions, promises and flags to update the items quantity in the database but none helps.
This is my code for to get and update the item's quantity
const Express = require("express");
const app = Express.Router();
const Menu = require("../../models/Menu");
const Order = require("../../models/order");
const User = require("../../models/user");
app.post(
"/create",
async function(req, res) {
var myorder = {};
var orderList = [];
var ordDetail = [];
var UpdateMenus = [];
orderList = JSON.parse(JSON.stringify(req.body["OD"]));
if(orderList.length>0){
const user = await User.findOne({ _id: req.user.id })
.then(user => {
if (!user) {
return res.status(400).json({ error: "User Not Found" });
}
})
.then(() => {
var order = Order({
user: req.user.id
});
myorder = order;
(async function loop() {
for (i = 0; i < orderList.length; i++) {
const ordt = new Object({
menu: orderList[i]["menuId"],
order: myorder.id,
prize: orderList[i]["prize"],
quantity: orderList[i]["quantity"]
});
await Menu.findOne({ _id: orderList[i]["menuId"] })
.exec()
.then(menu => {
if (menu) {
if (menu.quantity >= ordt.quantity) {
menu.quantity = menu.quantity - ordt.quantity;
const editmenu = menu;
(async function updateTheMenu() {
await Menu.findOneAndUpdate(
{ _id: menu.id },
{ $set: editmenu },
{
new: true,
useFindAndModify: false
}
).then(updateMenu => {
console.log(updateMenu);
ordDetail.push(ordt);
});
})();
} else {
return res.status(400).json({
error:
menu.MenuText +
"" +
ordt.quantity +
" Qunatity Is Not Available"
});
}
}
});
}
})();
}).then(()=>{
order
.save()
.then(order => {
if (!order) {
return res.json({ error: "Order is not saved" });
}
res.status(200).json(order);
})
.catch(error => {
return res
.status(400)
.json({ error: "Fields are Not Correct" });
});
});
}
}
);

Answer 1

There are few things wrong with your code:
If you use await then you don't need to use then. You can just assign to a variable. Example:
const menu = await Menu.findOne({ _id: orderList[i]["menuId"] })
You don't need to wrap your loop and every await call in async functions. They are already in an async function.
You can write your response handler like this:
app.post('/create', async function(req, res) {
var myorder = {};
var orderList = [];
var ordDetail = [];
var UpdateMenus = [];
orderList = JSON.parse(JSON.stringify(req.body['OD']));
if (orderList.length > 0) {
const user = await User.findOne({ _id: req.user.id });
if (!user) {
return res.status(400).json({ error: 'User Not Found' });
}
var order = Order({
user: req.user.id
});
myorder = order;
for (i = 0; i < orderList.length; i++) {
const ordt = new Object({
menu: orderList[i]['menuId'],
order: myorder.id,
prize: orderList[i]['prize'],
quantity: orderList[i]['quantity']
});
const menu = await Menu.findOne({ _id: orderList[i]['menuId'] });
if (menu) {
if (menu.quantity >= ordt.quantity) {
menu.quantity = menu.quantity - ordt.quantity;
const editmenu = menu;
const updateMenu = await Menu.findOneAndUpdate(
{ _id: menu.id },
{ $set: editmenu },
{
new: true,
useFindAndModify: false
}
);
console.log(updateMenu);
ordDetail.push(ordt);
} else {
return res
.status(400)
.json({
error:
menu.MenuText +
'' +
ordt.quantity +
' Qunatity Is Not Available'
});
}
}
}
try {
const savedOrder = await order.save();
if (!savedOrder) {
return res.json({ error: 'Order is not saved' });
}
res.status(200).json(savedOrder);
} catch (error) {
return res.status(400).json({ error: 'Fields are Not Correct' });
}
}
});