Express - Nodejs external rest api call - node.js

Question

I want to make a backend call to an external api's and populate my page with the results. What is the best way to do this?
The "request.get" call is asynchronous, so I understand the code below is erroneous. However, I have written it in that fashion so that I can explain what I want to actually do.
Further, I may have 5-6 external api, is there a way to make this asynchronous for every api but synchronous get call?
This is how my current code looks like:
var express = require('express');
var request = require('request');
var router = express.Router();
/* GET home page. */
router.get('/', function(req, res, next) {
var body = getRawApiResponse("someURL");
console.log("Index >" + body);
res.render('index', { title: 'Express', api: "some", body: body});
});
function getRawApiResponse(api){
request.get({
uri: api,
},
function(error, response, body){
if (!error && response.statusCode === 200) {
console.log("Index > Raw Api Response: " + body);
} else {
console.log(error);
}
});
}

Answer 1

You can wrap getRawApiResponse() in a promise
function getRawApiResponse(api){
return new Promise(function(resolve, reject){
request.get({
uri: api,
},
function(error, response, body){
if (!error && response.statusCode === 200) {
resolve(body)
} else {
reject(error)
}
});
});
}
which resolves on success and rejects in case of an error then you can chain it inside the get request like
router.get('/', function(req, res, next) {
getRawApiResponse("someURL")
.then(function(body){
res.render('index', { title: 'Express', api: "some", body: body});
})
.catch(err){
// do something
}
});

Answer 2

Look into Promises or async/await. You can use them to call your async apis and wait for the response making the call synchronous.
http://bluebirdjs.com/docs/getting-started.html
A Sample code of async/ await which u can modify for ur purpose is as below:
try{
let orderDetails = await MongoHelper.findOneByCriteria(MongoCollections.ORDER,searchCriteria);
}catch(err){
return err;
}
MongoHelper.findOneByCriteria = (collectionName, criteria) => {
return new Promise((resolve, reject) => {
db.collection(collectionName).find(criteria).toArray()
.then((results) => {
if (results.length > 0) {
resolve(results[0]);
} else {
resolve(null);
}
});
});
}

Answer 3

The best way is to use Promises to avoid callbacks hell. If you can use node.js v7.6 or higher, it could be much easier with async/await.
router.get('/', function(req, res, next) {
getRawApiResponse("someURL")
.then(body => {
console.log("Index >" + body);
res.render('index', { title: 'Express', api: "some", body: body});
});
});
function getRawApiResponse(uri) {
return new Promise((resolve, reject) => {
request.get({ uri }, (error, response, body) => {
if (err) {
reject(err);
}
resolve(body);
});
});
}
In the example about I use promisification to return a promise from getRawApiResponse, but there is already a module which do the same https://github.com/request/request-promise.