Using deferred and when

Question

I make an ajax call in a loop, the ajax call is in the class self.fileUpload:

$.when.apply($, $.map($('.file-new'), function(fileNewTemplate, i) {

        var formData = new FormData();

        return self.fileUpload.upload(formData).then(function(data){
            return $.Deferred().resolveWith(this);

        }).fail(function(){
            console.log('ajax call failed');

        });

    })).done(function(){
        console.log('when done');

    })
    .always(function(){
        console.log('when always');
    })
    .fail(function(){
        console.log('when fail');
    })

The problem is, when one ajax call fails, the fail of the when is called. I need a solution that would call done or always once all promises are returned, despite whether some or all failed.

I checked out the answers here:

$.Deferred: How to detect when every promise has been executed

And as you can see from the above code, I have implemented the accepted solution.

The problem is, done is still never called and always is called as soon as one ajax call fails.

Where am I going wrong?

No, you did not implement my solution from the answer there. The callback that returns a resolved Deferred is the *second* argument to `.then()`, the first one is `null`! — Bergi, Jun 24 '14 at 11:50

score 1 · Accepted Answer · answered Jun 24 '14 at 11:06

1

Where am I going wrong?

It's not you, but how $.when() works.

But you can easily implement a function that would resolve after all promises either resolve or reject:

var waitAllRegardlessResult = function(promises) {
    var cnt = promises.length,
        d = $.Deferred(),
        countHandler = function() {
            if (--cnt == 0) {
                d.resolve();
            }
        };

    promises.map(function(promise) {
        promise.always(countHandler);
    });

    return d.promise();
};

Demo: http://jsfiddle.net/X38JT/

So this function will return a promise object that is resolved after all promises passed as an array either resolved or rejected

answered Jun 24 '14 at 11:06

zerkms

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Where does this fit in with my code? How does it loop through all my ajax requests? – panthro Jun 24 '14 at 11:09
@panthro: you use the given function instead of `$.when()`. On the jsfiddle page you can see the usage example – zerkms Jun 24 '14 at 11:10
Sorry, your fiddle is not clear. Where is promises passed into the above method? – panthro Jun 24 '14 at 11:16
@panthro: line 20: `waitAllRegardlessResult([a, b])` --- both `a` and `b` are promises defined in lines 1 and 2 – zerkms Jun 24 '14 at 11:17
so what promises should I pass into the method? – panthro Jun 24 '14 at 11:18
@panthro: the promises you're awaiting of resolve for. In your case it's presumably what `self.fileUpload.upload` returns – zerkms Jun 24 '14 at 11:21

Using deferred and when

1 Answers1