CODEWITHSUNDEEP
javascriptnode.jsrequestpromise
Trung Tran
Trung Tran

Reputation: 13721

Multiple node.js requests

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!

Upvotes: 0

Views: 220

Answers (3)

Bek
Bek

Reputation: 3207

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

Upvotes: 0

BlackMamba
BlackMamba

Reputation: 10254

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.

Upvotes: 2

t3dodson
t3dodson

Reputation: 4007

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);
            });
        });
    });
};

Upvotes: 0

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