Ensure that you wait for all asynchronous $http requests to finish in AngularJS before continuing

Question

Ensure that you wait for all asynchronous $http requests to finish in AngularJS before continuing

I am facing a challenge with a page that generates a varying number of $http requests based on the length of a certain variable. I aim to update the scope with the data only after all requests have been completed. Without relying on jQuery for this project, I seek a solution that does not involve jQuery. Currently, the data is being sent to the scope as each request finishes, which is not the desired behavior.

Below is a snippet of the code I have implemented so far:

for (var a = 0; a < subs.length; a++) {
  $http.get(url).success(function (data) {
    for (var i = 0; i < data.children.length; i++) {
      rData[data.children.name] = data.children.age;
    }
  });
}

One part that concerns me is the argument required for $q.all() method, which is not clearly explained in the Angular documentation, leaving me unsure of how to proceed.

$q.all().then(function () {
  $scope.rData = rData;
});

I appreciate any assistance in resolving this issue. Thank you.

javascript angularjs

Answer 1

Answer №1

$http always returns a promise that can be utilized with the $q.all function.

var one = $http.get(...);
var two = $http.get(...);

$q.all([one, two]).then(...);

More information on this behavior can be found in the official documentation:

all(promises)

promises - An array or hash of promises.

To implement this in your case, you will need to create an array and push all the calls into it in a loop. This will allow you to use $q.all(…) on your array similarly to the example provided above:

var arr = [];

for (var a = 0; a < subs.length; ++a) {
    arr.push($http.get(url));
}

$q.all(arr).then(function (ret) {
    // ret[0] contains the response of the first call
    // ret[1] contains the second response
    // and so on.
});

Answer 2

$http always returns a promise that can be utilized with the $q.all function.

var one = $http.get(...);
var two = $http.get(...);

$q.all([one, two]).then(...);

More information on this behavior can be found in the official documentation:

all(promises)

promises - An array or hash of promises.

To implement this in your case, you will need to create an array and push all the calls into it in a loop. This will allow you to use $q.all(…) on your array similarly to the example provided above:

var arr = [];

for (var a = 0; a < subs.length; ++a) {
    arr.push($http.get(url));
}

$q.all(arr).then(function (ret) {
    // ret[0] contains the response of the first call
    // ret[1] contains the second response
    // and so on.
});

Ensure that you wait for all asynchronous $http requests to finish in AngularJS before continuing

Answer №1

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