Returning body of a request function inside a variable - node.js

Question

I have an endpoint in my node backend in which will need to retrieve for each item in my Adhoc collection from my local database the _id along with a number value which I need to calculate from the body of a request() function in an array of objects. The objects will be like this
{id: "id", sum: 3}
To do this I need to iterate through the Adhocs with a for loop and make a request for each to get the sum value and I need to be able to store these values before I have all of them and res.send() the array to the front end. I am having trouble storing the sum value in a variable. I have provided below the code of the request.
let theSum = request(options, function (error, response, body) {
if (error) throw new Error(error);
console.log(
'Response: ' + response.statusCode + ' ' + response.statusMessage
);
let bodyy = JSON.parse(body);
let sum = bodyy.fields.timetracking.originalEstimateSeconds / 3600 * theRate;
return sum;
});
I know this is wrong as the return statement is for the function inside the request function so it won't return the sum to my variable. And adding another callback function will basically be the same scenario. Anyone has any suggestions of how I can store the value from the request function so I can make further calls?

Answer 1

I found an answer that works for me pretty well. I didn't try Terry's answer above but I suppose that works as well since it's using Promise as well as me. What I've done is in a function I wrapped the request call in a Promise with a callback which is returned. Code below:
function asyncRequest (url) {
return new Promise (function (resolve, reject) {
var options = {
url: 'http://localhost:8080/rest/' + url,
auth: { username: 'username', password: 'password' },
headers: {
'Accept': 'application/json'
}
}
request(options, function (err, response, body) {
if (err) reject(err);
resolve(JSON.parse(body))
});
})
}
When I want to retrieve something I just have something like this:
let json = await asyncRequest('agile/1.0/issue/'+ adhoc[u].jIssue);
And that variable has the body of the request function inside and I can use it.

Answer 2

You can use async and await along with request-promise-native to loop over your objects and get the list of results you wish to have.
You can call the readEstimates function in a express.get( ).. handler as long as the handler is asynchronous (or you can use readEstimates().then(..)).
Now, we will wrap an error handler around the readEstimates call since, this could potentially throw an error.
For example:
const rp = require('request-promise-native');
async function readEstimates() {
const sumList = [];
for(const adhoc of adhocList) {
// Set your options here, e.g. url for each request.. by setting json to true we don't need to JSON.parse the body.
let options = { url: SOME_URL, json: true, resolveWithFullResponse: true };
let response = await rp(options);
console.log('Response: ' + response.statusCode + ' ' + response.statusMessage);
const sum = response.body.fields.timetracking.originalEstimateSeconds / 3600 * theRate;
sumList.push(sum);
}
return sumList;
}
async function testReadEstimates() {
try {
const sumList = await readEstimates();
console.log("Sumlist:", sumList);
} catch (error) {
console.error("testReadEstimates: An error has occurred:", error);
}
}
testReadEstimates();
You can also use readEstimates in an Express route:
app.get('/', async (req, res) => {
try {
const sumList = await readEstimates();
res.json({sumList}); // Send the list to the client.
} catch (error) {
console.error("/: An error has occurred:", error);
res.status(500).send("an error has occurred");
}
})