Multiple node.js requests

Question

My controller is using the request package to make server-side HTTP requests to another API. My question is how can I make MULTIPLE of these requests? Here is my current code:

** UPDATED CODE **

module.exports = function (req, res) {
var context = {};
request('http://localhost:3000/api/single_project/' + req.params.id, function (err, resp1, body) {
    context.first = JSON.parse(body);
    request('http://localhost:3001/api/reports/' + req.params.id, function (err, resp2, body2) {
        context.second = JSON.parse(body2); //this line throws 'SyntaxError: Unexpected token u' error
        res.render('../views/project', context);
    });
});

};

I need to make two more of those calls and send the data returned from it to my template...

Can someone help?

Thanks in advance!

BlackMamba · Accepted Answer · 2015-12-29 02:28:38Z

2

function makePromise (url) {
  return Promise(function(resolve, reject) {

      request(url, function(err, resp, body) {
        if (err) reject(err);
        resolve(JSON.parse(body));
      });

  });
}

module.exprts = function (req, res) {
  let urls = ['http://localhost:3000/api/1st', 
              'http://localhost:3000/api/2st',
              'http://localhost:3000/api/3st'].map((url) => makePromise(url));

  Promise
    .all(urls)
    .then(function(result) {
      res.render('../views/project', {'first': result[0], 'second': result[1], 'third': result[2]});
    })
    .catch(function(error){
      res.end(error);
    });
}

You can use Promise lib in latest nodejs.

answered Dec 29, 2015 at 2:28

BlackMamba

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Community · Accepted Answer · 2020-06-20 09:12:55Z

0

Simple solution

Nest request calls. This is how you can handle the dependency between requests. Just make sure your parameters are unique across scopes if needed.

module.exports = function (req, res) {
    var context = {};
    request('http://localhost:3000/api/1st', function (err, resp1, body) {
        var context.first = JSON.parse(body);
        request('http://localhost:3000/api/2nd', function (err, resp2, body) {
            context.second = JSON.parse(body);
            request('http://localhost:3000/api/3rd', function (err, resp3, body) {
                context.third = JSON.parse(body);
                res.render('../views/project', context);
            });
        });
    });
};

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Dec 29, 2015 at 2:13

t3dodson

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4 Comments

Trung Tran Over a year ago

Is this technique blocking or async?

t3dodson Over a year ago

@user1547174 This is async. The call backs fire when the response is returned.

Bek Over a year ago

@t3dodson this is executed serially and one failure in chain leads to failure of whole chain, it is better to use promises as it helps to avoud heavy nesting

Julian Over a year ago

Talking about a async. Do yourself a favour, avoid this callback hell, and give the npm module async a spin.

Bek · Accepted Answer · 2015-12-31 09:07:55Z

0

Simplest way if you use bluebird promise library:

var Promise = require('bluebird');
var request = Promise.promisify(require('request'));

module.exports = function (req, res) {
  var id = req.params.id;
  var urls = [
   'http://localhost:3000/api/1st/' + id,
   'http://localhost:3000/api/2st/' + id,
   'http://localhost:3000/api/3st/' + id
  ];

  var allRequests = urls.map(function(url) { return request(url); });

  Promise.settle(allRequests)
    .map(JSON.parse)
    .spread(function(json1, json2, json3) {
      res.render('../views/project', { json1: json1 , json2: json2, json3: json3  });
    });
});

it executes all requests even if one (or more) fails

edited Dec 31, 2015 at 9:07

answered Dec 29, 2015 at 6:22

Bek

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