Pass parameter to $q.all callback - angularjs

Question

I need to pass some local parameter to the $q.all callback
var actions = [];
var jsonFiles = ["a.json","b.json","c.json"];
for(var index=0; index<3; index++){
actions.push($http.get('content/' + jsonFiles[index]);
}
$q.all(actions).then(function (values) {
console.log(index) // Need to print current request index
}
current output is of course 3,3,3
I need to print 0,1,2 according to the response order (it can be 1,0,2 or other combination)
I've created a jsfiddle with my issue - http://jsfiddle.net/dorcohen/n30er4ap/

Answer 1

If I understand you correctly , you should use params :
for (var index = 0; index < 3; index++)
{
actions.push($http.get( jsonFiles[index], {params:{"idx": index }}));
}
Then :
$q.all(actions).then(function(values) {
for (var i=0;i<values.length;i++)
$scope.indexes.push(values[i].config.params.idx);
})
Fiddle

Answer 2

OK, so it is rather overkill, but it will work I think
for(var index=0; index<3; index++){
actions.push($q.all([
$q.resolve(index),
$http.get('content/' + jsonFiles[index]);
]);
}

Answer 3

While #Royi's answer is correct, if will not work for "non-http" promises.
A nice workaround which will work for kind of promises is by using the anti-pattern of creating a defered object as a wrapper and resolving your own custom object.
While this is a anti-pattern, there are some cases you want to use it like here.
HTML:
<div ng-app="app">
<div ng-controller="ctrl">
<button ng-click="do()">
Click
</button>
</div>
</div>
JS:
angular.module('app', []).
controller('ctrl', function($scope, $http, $q) {
$scope.do = function() {
var acts = [];
for (var i = 0; i < 3; i++) {
var defer = $q.defer(); // create your own deferred object
// worked with a dummy promise - you can use what ever promise you want
var promise = $q.when({
obj: i
});
promise.then(
// closure for the current deferred obj + index since we are in a loop
function(d,idx) {
return function(item) {
d.resolve({res: item, index:idx}); // resolve my deferred object when I want and create a complex object with the index and the "real response"
}
}(defer,i));
acts.push(defer.promise);
}
$q.all(acts).then(function(res) {
console.log(res);
});
}
});
JSFIDDLE.