sequential request in node js - node.js

Question

I'm learning to make an API in node js with express library
i have two things : product , order
and each order has an address , one or more product and a total price which is based by price of products
when i try to save an order i just pass the products IDs so in code i should get the products and sum their prices plus i want to show the products in the response so what i did was to put the ids in an array and i executed a foreach loop in array and in every loop i get the product and push it in an array .
the problem is that the response (actually every code after foreach loop) is executed before i get the products,
i have searched about Async/Await and i tried to implement it but it didn't work
my code is like this
function getproductpromis(options){
return new Promise((resolve,reject) =>{
http.get(options, resolt =>{
let data ;
resolt.on('data', d => {
data +=d;
})
resolt.on('end', f =>{
resolve (data);
})
resolt.on('error', e =>{
reject(e);
console.log(e);
})
});
});
}
async function getproduct(element){
let object;
const options = {
hostname:'localhost',
port:5000,
path:'/products/'+element,
mathod:'GET'
}
const request_call = await getproductpromis(options);
console.log('request_call');
console.log(request_call);
return request_call;
}
router.post('/',(req,res,next) => {
let prod;
console.log(req.body.products);
const ids = req.body.products;
let totalprice = 0;
let objects =[];
ids.forEach(element => {
prod = getproduct(element);
console.log('prod');
console.log(prod);
objects.push(prod);
});
res.status(200).json({
objects
});
}
and here is my log:
[ '5dab2706baab4b1e90dc30ff', '5dab2792f0662d4f54bbf1f1' ]
prod
Promise { <pending> }
prod
Promise { <pending> }
POST /orders 200 56.974 ms - 19
{ _id: 5dab2706baab4b1e90dc30ff,
name: 'langero',
quantity: 5,
price: 1500,
__v: 0 }
GET /products/5dab2706baab4b1e90dc30ff 200 208.973 ms - 114
request_call
undefined{"massage":"product found","product":{"ID":"5dab2706baab4b1e90dc30ff","name":"langero","quantity":5,"price":1500}}
{ _id: 5dab2792f0662d4f54bbf1f1,
name: 'langer',
quantity: 5,
price: 1500,
__v: 0 }
GET /products/5dab2792f0662d4f54bbf1f1 200 1172.254 ms - 113
request_call
undefined{"massage":"product found","product":{"ID":"5dab2792f0662d4f54bbf1f1","name":"langer","quantity":5,"price":1500}}
and response i get in postman
response

Answer 1

Change your forEach loop to for...of loop
[https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of]
Here is your updated router.post using async/await and for...of loop
router.post('/',async (req,res,next) => {
let prod;
console.log(req.body.products);
const ids = req.body.products;
let totalprice = 0;
let objects =[];
for (let element of ids) {
prod = await getproduct(element);
console.log('prod');
console.log(prod);
objects.push(prod);
}
res.status(200).json({
objects
});
}

Answer 2

So you want to execute and an array of Promises, you're on the right track but may I point you in the direction of Async/Await. Here I marked your router.post callback as async so I can use await. I use Array.map to return an array of promises that get passed to Promise.all
router.post("/", async (req, res, next) => {
const ids = req.body.products;
const objects = await Promise.all(
ids.map((id) => {
return getproduct(id);
})
);
res.status(200).json({
objects
});
});