The error message "angularjs is unable to assign a value to the property 'students' as it is

After setting ClassesServices to the classes array, I tried adding students of the class to a new property called classes.students. However, I encountered an error message saying 'Cannot set property 'students' of undefined.'

$scope.classes = [];
$scope.getClasses = function(){
            ClassesServices.all().then(function(data){
                $scope.classes = data;
                for(var i = 0; i < $scope.classes.length; i++){
                    ClassesServices.getStudentsbyClassId($scope.classes[i].id).then(function(data){
                        $scope.classes[i].students = data;
                    });
                } 
            });
        };

        $scope.getClasses();

Your help is much appreciated in resolving this issue.

I attempted to create a separate function to add students but ended up with an 'undefined' outcome. Hence, I'm unsure if using a separate function as shown below would be feasible.

$scope.getClasses = function(){
            ClassesServices.all().then(function(data){
                $scope.classes = data;
                for(var i = 0; i < $scope.classes.length; i++){
                        $scope.getStudentsbyClassId($scope.classes[i].students, $scope.classes[i].id);
                    });
                } 
            });
        };

$scope.getStudentsbyClassId = function (students){
    ClassesServices.getStudentsbyClassId(id).then(function(data){
        students = data;
};
        $scope.getClasses();

Answer №1

It appears there are multiple issues to address in the code provided.

Initially, there is a concern with defining a function within a loop as demonstrated in the first example - resulting in unexpected outcomes (source).

Furthermore, in the second approach, there seems to be confusion regarding the passing of ".students", which is undefined at that point, to "$scope.getStudentsbyClassId". It is expected for this function to be a property within the array, but it does not work in that manner.

A suggestion is to obtain the promises from "getStudentsbyClassId" and utilize $q.all to handle them together.

(Additionally, unless there is an intention to call a function from the View, it is unnecessary to define it on the $scope)

$scope.classes = [];
ClassesServices.all()
  .then(function(classesData){
     $scope.classes = classesData;

     var promisesForStudents = [];
     for(var i = 0; i < $scope.classes.length; i++){
       var classId = $scope.classes[i].id;
       promisesForStudent[i] = ClassesServices.getStudentsbyClassId(classId);
     }

     return $q.all(promisesForStudents);
  })
  .then(function(studentsData){
     for(var i = 0; i < studentsData.length; i++){
        $scope.classes[i].students = studentsData[i];
     }
  })

Answer №2

It's important to note the difference between $scope.classes and $scope.Classes in Angular. The capitalization of letters matters in this case. Simply switching your references from $scope.Classes to $scope.classes should resolve any issues you may be experiencing.

Answer №3

Consider adjusting classes to lowercase in every instance where you currently have "Classes". keep in mind that object and variable names are case-sensitive, so by using different cases you could be referencing different objects.

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