How can I make node js synchronize?

Question

I used promise as suggested but still I have a problem that I can console.log my array.

here is what I did:

exports.getData = function(request, response) {

    userEmail = request.body.user;

function delay(ms){ // takes amount of milliseconds
  return new Promise(function(resolve, reject){
    setTimeout(function(){ // when the time is up
      resolve(); // change the promise to the fulfilled state
    }, ms);
  });
}

    Wish.find({userEmail}).exec( function(err, docs) {
        //console.log("docs "+docs);
        var wishArray = new Array();


            for (var i=0; i<docs.length; i++) {
            if (docs[i].sub=='party') { 
                var id = docs[i].num;
                delay(100).then(function(){
                    Party.find({id}).exec(function(err, details) {
                      console.log("5");
                    wishArray.push(details);
                });
            });
            }  
        } 
    });
    delay(700).then(function(){
    console.log(wishArray);
});

}

I tried make the number of the second delay larger but it didn't work. anyone has any idea how can I fix it?

you have 2 `console.log(wishArray);` the first one will work correctly — Iceman, Jul 12 '16 at 09:45
right the second one is not working I did that so I can see that the array is not empty... — user3488862, Jul 12 '16 at 09:46

enRaiser · Accepted Answer · 2016-07-12T12:37:23.600

2

You can avoid logging untill wishArray is fully populated, this way.

exports.getData = function(request, response) {
userEmail = request.body.user;

Wish.find({userEmail}).exec( function(err, docs) {
    console.log("docs "+docs);
    var wishArray = new Array();
    for (var i=0; i<docs.length; i++) {

        if (docs[i].sub=='party') {
            console.log("--------------------"); 
            var id = docs[i].num;
            Party.find({id}).exec(function(err, details) {
                wishArray.push(details);
                  if(wishArray.length == docs.length){
                      console.log(wishArray);
                  }

            });
        }  
    }
    console.log("***************************"); 

});

}

in many other complex use cases people used array of deferred queries. but your case is simple one you can catch hold of it just by length of array.

edited Jul 12 '16 at 12:37

answered Jul 12 '16 at 09:51

enRaiser

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this will not wait. I suggest a promise(). – Iceman Jul 12 '16 at 09:54
@Iceman how do I use it so both function will work? – user3488862 Jul 12 '16 at 10:47
@user3488862 give me 20mins, and ill post an answer using promise. sorry for the delay. – Iceman Jul 12 '16 at 10:50
@Iceman thanks! I really appreciate it! – user3488862 Jul 12 '16 at 10:56
@Iceman yes i'm here – user3488862 Jul 12 '16 at 11:30
I have edited my answer with full code. just in case , If you have misunderstood. it, I already said there is a promise method. but did not suggested it because it may be heavy. I don't know what the hale , some jealous person has downvoted me. as I never said this is perfect answer... – enRaiser Jul 12 '16 at 12:19
@enRaiser wow thanks!!! life saver! – user3488862 Jul 12 '16 at 12:32
@enRaiser :D no worries, I've upvoted you . user3488862 cheers. – Iceman Jul 12 '16 at 19:54

How can I make node js synchronize?

1 Answers1