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up vote 0 down vote favorite

I'm trying to assign array elements in a for loop with asynchronous results of a call to a ngResource action.

for ( var i = 0; i < projs.length; i++) {
    $scope.projets[i].redacteur = new Object(); // the Object where the result will be stored
    var param = new Object();
    param.email = projs[i].redacteurEmail;
    Agent.read(param, function(data) {
        $scope.projets[i].redacteur = data;
    });


}

The problem is : when the callback function is executed (when the data is received), i is out of bounds (it passed the last i++). Then the data received is assigned to a nonexistent object.

Any idea of a solution to this issue ?

share|improve this question
2  
possible duplicate of Javascript infamous Loop problem? – Fabrício Matté Nov 14 '13 at 16:10
2  
and Problem with loop – Fabrício Matté Nov 14 '13 at 16:11
2  
and Weird value for counter variable in javascript – Fabrício Matté Nov 14 '13 at 16:11
2  
also Why is the answer to this 10? – Fabrício Matté Nov 14 '13 at 16:12
2  
and this one How to generate event handlers with loop in Javascript? – Fabrício Matté Nov 14 '13 at 16:12
up vote 1 down vote accepted

I solved this issue by putting the call to the callback function in a closure. With my example, it looks like that :

for (var i = 0; i < projs.length; i++) {
    $scope.projets[i].redacteur = new Object(); // the Object where the result will be stored
    var param = new Object();
    param.email = projs[i].redacteurEmail;
    (function(i) {
        Agent.read(param, function(data) {
            $scope.projets[i].redacteur = data;
        });
    })(i);
}
share|improve this answer
    
Trop fort !! You saved my skin here ! I now need to read about javascript closures. – Stephane Oct 8 '14 at 13:11
up vote 0 down vote

I had a similar issue, and I solved it by using Promises. The basic idea is that I send the index of the array as a parameter to my asynchronous request callback, and then I can handle it when the response arrives. Hope that helps.

share|improve this answer
up vote 0 down vote

If I understand your issue correctly, I believe this may work.

myData = Agent.read(param, function() {
    $scope.projets[i].redacteur = myData;
});

This is the approach I have used. I'm still new to Angular, but my understanding is that myData becomes a deferred promise. As a deferred promise it must be resolved prior to use. Please, someone who has more experience Angular and deferred promises chime in.

share|improve this answer

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