Angularjs q all

Question

I have implemented the  q all in angularjs  but I can not make the code work  Here is my code    UploadService uploadQuestion   function questions            var promises                for var i   0   i  lt  questions length   i                  var deffered     q defer                var question    questions i                  http                    url      upload question                   method   POST                   data    question                             success function data                   deffered resolve data                               error function error                   deffered reject                                 promises push deffered promise                      return  q all promises           And here is my controller which call the services   uploadService uploadQuestion questions  then function datas         the datas can not be retrieved although the server has responded         function errors         errors can not be retrieved also       I think there is some problem setting up  q all in my service

User · Answer

The issue seems to be that you are adding the deffered.promise when deffered is itself the promise you should be adding:

Try changing to promises.push(deffered); so you don't add the unwrapped promise to the array.

 UploadService.uploadQuestion = function(questions){

            var promises = [];

            for(var i = 0 ; i < questions.length ; i++){

                var deffered  = $q.defer();
                var question  = questions[i]; 

                $http({

                    url   : 'upload/question',
                    method: 'POST',
                    data  : question
                }).
                success(function(data){
                    deffered.resolve(data);
                }).
                error(function(error){
                    deffered.reject();
                });

                promises.push(deffered);
            }

            return $q.all(promises);
        }

User · Answer

http is a promise too  you can make it simpler   return  q all tasks map function d           return  http post  upload tasks  d  then someProcessCallback  onErrorCallback

User · Answer

In javascript there are no block-level scopes only function-level scopes   Read this article about javaScript Scoping and Hoisting   See how I debugged your code   var deferred    q defer    deferred count   i   console log deferred count      0 1 2 3 4 5 -- lt  all deferred objects     some code   success function data      console log deferred count      5 5 5 5 5 5 -- lt  only the last deferred object    deferred resolve data         When you write var deferred   q defer    inside a for loop it s hoisted to the top of the function  it means that javascript declares this variable on the function scope outside of the for loop  With each loop  the last deferred is overriding the previous one  there is no block-level scope to save a reference to that object  When asynchronous callbacks  success   error  are invoked  they reference only the last deferred object and only it gets resolved  so  q all is never resolved because it still waits for other deferred objects  What you need is to create an anonymous function for each item you iterate  Since functions do have scopes  the reference to the deferred objects are preserved in a closure scope even after functions are executed  As  dfsq commented  There is no need to manually construct a new deferred object since  http itself returns a promise     Solution with angular forEach   Here is a demo plunker  http   plnkr co edit NGMp4ycmaCqVOmgohN53 p preview  UploadService uploadQuestion   function questions        var promises            angular forEach questions   function question             var promise    http               url      upload question               method   POST               data    question                      promises push promise                 return  q all promises       My favorite way is to use Array map   Here is a demo plunker  http   plnkr co edit KYeTWUyxJR4mlU77svw9 p preview  UploadService uploadQuestion   function questions        var promises   questions map function question             return  http               url      upload question               method   POST               data    question                           return  q all promises

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