Angular promises using multiple http requests

Question

I have read a few forum posts before on angular promises but can't get it to work in my instance. I am using nodejs /locomotive for the backend and Angular form the frontend.

I have the following code in a controller, basically I want to use the path to slides.path, how would I go about doing this using promises? any help would be gratefully received.

function ProductCtrl($scope, $http, $q) {

    $scope.events = [];
    $scope.times = [];

    var html = [];
    var chapters = [];
    var path;

    //var paPromise = $q.defer();

    $http({
        url: '/show',
        method: 'GET',
        params: { eventid:$scope.$routeParams.eventid}

    }).success(function(response, code) {

        $scope.events = response;

        angular.forEach($scope.events.slides, function(slide) {

            $http({
                url: '/upload',
                method: 'GET',
                params: {uploadid: slide.upload.toString()}

            }).success(function(response, code) {
                return "http://www.example.com/"+response.path;

            },path);

            slide.path = path;

            chapters.push(slide);

        });

    });
}

You are doing it with promises. $http returns a promise, and the success call is only invoked when the promise is resolved. What exactly are you having a problem with? — adrichman
– adrichman, Commented Apr 16, 2014 at 2:47
Unless you want to go full FRP or enable legacy auto unwinding mode. I'm not sure what you want to accomplish. — Benjamin Gruenbaum
– Benjamin Gruenbaum, Commented Apr 16, 2014 at 4:59

Konstantin Krass · Accepted Answer · 2014-04-16 11:26:34Z

4

You can use $q.all do get this multiple promise problem done. Like this:

function ProductCtrl($scope, $http, $q) {

$scope.events = [];
$scope.times = [];

var html = [];

var path;

function fetchChapter() {
    var chapters = [];

    var httpPromise = $http({
        url: '/show',
        method: 'GET',
        params: {
            eventid: $scope.$routeParams.eventid
        }
    });

    //Return the value http Promise
    return httpPromise.then(function (response) {
        $scope.events = response;
        var promises = [];
        angular.forEach($scope.events.slides, function (slide) {

            var inPromise = $http({
                url: '/upload',
                method: 'GET',
                params: {
                    uploadid: slide.upload.toString()
                }
            }).then(function (response, code) {
                //each promise makes sure, that he pushes the data into the chapters
                slide.path = "http://www.example.com/" + response.path;
                chapters.push(slide);
            });
            //Push the promise into an array
            promises.push(inPromise);
        });
        //return the promise from the $q.all, that makes sure, that all pushed promises are ready and return the chapters.
        return $q.all(promises).then(function () {
            return chapters;
        });
    });
}

fetchChapter().then(function(chapters){
   //populate here 
});

}

The httpPromise will return the promise from $q.all.

EDIT: How to fetch the data then Wrap a function around, i did with fetchChapter and pass a function into the then there will be the value you need as a parameter.

edited Apr 16, 2014 at 11:26

answered Apr 16, 2014 at 6:29

Konstantin Krass

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4 Comments

Benjamin Gruenbaum Over a year ago

Eh. why not return chapter from the promise? You can simply map the slices to promises on them.

Konstantin Krass Over a year ago

the "s" was missing ^^ chapters.push(slide)

Richard Mc Over a year ago

thanks for the reply how would I use the var chapters to populate a div outside the httpromise

Richard Mc Over a year ago

That did the trick and I have began to understand promises, cool, cheers

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