Array.Push doesn't work on NodeJS

Question

I can't make this code works, i'm trying to generate 5 randoms items from my DB and store them into the array (dato), but when i print it seems to be empty

/* GET users listing. */
router.get('/', function (request, response) {
    var dato = new Array();

    for(var i=0;i<7;i++){
        almuerzoSchema.findRandom({}, {}, {limit: 5}, function(err, results) {
            if (!err) {
                results.forEach(function (record) {
                    dato.push(record.nombre);
                });
            }
        });
    }
    console.log(dato);
    response.render('almuerzo.jade',{almuerzovar: dato});
});

The console.log(dato) shows:

[]

if i print "record.nombre" on console.log it shows correctly

before the for loop ends, you r trying to print the dato. For loop will run async. — Subburaj
– Subburaj, Commented Apr 29, 2016 at 5:02
Please learn how asynchronous programming Node.js works before writing any more code. There are quite a few things wrong with this route, e.g. your for loop is synchronous and is going to cause you quite a few problems. — Qix - MONICA WAS MISTREATED
– Qix - MONICA WAS MISTREATED, Commented Apr 29, 2016 at 5:06

mido · Accepted Answer · 2016-04-29 05:08:40Z

2

like Rayon said, the code is async, so change it to something like this( since async, I am using Promise):

/* GET users listing. */
router.get('/', function (request, response) {
    var dato = new Array(), promises =[];

    for(var i=0;i<7;i++){
        promises.push(promisifiedFindRandom())
    }

    Promise.all(promises).then(function(){
      console.log(dato);
      response.render('almuerzo.jade',{almuerzovar: dato});
    })

    function promisifiedFindRandom(){
      return new Promise(function(resolve, reject){
          almuerzoSchema.findRandom({}, {}, {limit: 5}, function(err, results) {
              if (!err) {
                  results.forEach(function (record) {
                      dato.push(record.nombre);
                  });
                  resolve();
              }else{
                resolve();
              }
          });            
      })
    }
});

Edit: node v4+ support promise natively, for older versions, you can use polyfill/shim

edited Apr 29, 2016 at 5:08

answered Apr 29, 2016 at 5:03

mido

25.2k15 gold badges99 silver badges123 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Rayon Over a year ago

almuerzoSchema.findRandom is in a loop buddy!

Saad Over a year ago

I think you meant else { reject(err); }

Collectives™ on Stack Overflow

Array.Push doesn't work on NodeJS

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related