Make http request from within a function - Node.js

Question

i'm writing a Web Service in node and i'm new with callbacks concept. I have in my routing file a route that receives url param - a Facebook access token, and should call the getMP function. This function creates http request to Facebook and retrieve some info I want to process later. so the route looks like this:

//route that recives parameter using defined parameters - enter FB access token to get  music info about it
app.get('/MP/:FBat', 
    function (req, res, next){
        res.header("Access-Control-Allow-Origin", "*");
        res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
        next(); 
    },

    function (req, res) {
    res.status(200).json(FB.getMP(req.params.FBat));
});

and the function getMP :

exports.getMP = function(access_token) {
request("https://graph.facebook.com/v2.5/me/music?access_token=" + access_token, function(error, response, body) {
    if (!error && response.statusCode == 200) {
        FB_MP = JSON.parse(body);
        // console.log(FB_MP); this returns ok
      }else{
        console.log(response.statusCode);
      }
    });

//return value - I wand to use it after the request has returned
return FB_MP;
}

What is the correct way of doing this? It works if the res is fast but of course its not good. any advice ? thanks

You need to keep it mind that javascript is asynchronous language, callback is the primary way of preserving function execution order by injecting the function into the another function — Yerken
– Yerken, Commented Feb 24, 2016 at 15:20

leobelizquierdo · Accepted Answer · 2016-02-24 15:31:41Z

You can use a library for promises like q and make the response after you get the necessary value inside the method then, try something like this:

//route that receives parameter using defined parameters - enter FB access    token to get  music info about it
app.get('/MP/:FBat', 
    function (req, res, next){
        res.header("Access-Control-Allow-Origin", "*");
        res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
        next(); 
    },

    function (req, res) {
        FB.getMP(req.params.FBat)
        .then(function(result){
            if(result){
                res.status(200).json(result);
            }
            else{
               console.log('do something about it');
            }
        });            
});

the code of getMP will be something like this:

var Q = requirie('q');
exports.getMP = function(access_token) {
    var deferred = Q.defer();
    request("https://graph.facebook.com/v2.5/me/music?access_token=" +  access_token, function(error, response, body) {
     if (!error && response.statusCode == 200) {
        FB_MP = JSON.parse(body);
        deferred.resolve(FB_MP);
      }else{
        deferred.resolve(false);
      }
    });

    //return value - I wand to use it after the request has returned
    return deferred.promise;
}

Also you can pass the req and res params to a kind of controller where you put the logic and then send the result to the view. Something like this:

//route that receives parameter using defined parameters - enter FB access  token to get  music info about it
var controller = require('path/to/controller');
app.get('/MP/:FBat', 
    function (req, res, next){
        res.header("Access-Control-Allow-Origin", "*");
        res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
        next(); 
    },

    function (req, res) {
        controller.getFacebookAccess(req, res, req.params.FBat);
});

The controller:

module.exports = function getFacebookAccess(req, res, access_token){
    request("https://graph.facebook.com/v2.5/me/music?access_token=" +  access_token, function(error, response, body) {
        if (!error && response.statusCode == 200) {
            FB_MP = JSON.parse(body);
            res.status(200).json(FB_MP);
          }else{
            res.send('do something about it');
          }
        });
    }
};

Collectives™ on Stack Overflow

Make http request from within a function - Node.js

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related