Generating proper options for select using ng-options - angularjs

Question

Trying to get the options in the select field to use the IDs in an array as values.
HTML looks like this:
<select class="form-control" name="activitySelector"
ng-model="item"
ng-change="changeActivity()"
ng-options="activity.id as activity.value for activity in activities">
<option value="">Nothing selected</option>
</select>
Controller:
angular.module('myApp')
.controller('ActivityCtrl', function ($scope, $rootScope) {
$scope.activities = [
{"id":"54be7f8","value":"Add New Activity"},
{"id":"5407968","value":"Activity 1"}
];
$scope.item = "";
$scope.changeActivity = function() {
console.log($scope.item); //prints undefined
}
});
Generated HTML looks like this:
<select ng-options="activity.id as activity.value for activity in activities" ng-change="changeActivity()" ng-model="item" class="form-control ng-pristine ng-valid">
<option value="" class="">Nothing selected</option>
<option value="0">Add New Activity</option>
<option value="1">Activity 1</option>
</select>
Questions that I have so far:
1- Why $scope.item prints undefined?
2- Why the options would use a consecutive value instead of the ID provided?

Answer 1

You can modify your code as follows in order for your html to render as you wish:
<select class="form-control" name="activitySelector"
ng-model="item"
ng-change="changeActivity()"
ng-options="activity.value for activity in activities track by activity.id">
<option value="">Nothing selected</option>
</select>
And in your controller now, you should change as follows:
$scope.changeActivity = function() {
console.log($scope.item.id);
console.log($scope.item.value);
}
Here is the Plunker: http://plnkr.co/edit/DWobFzvas9x4lhaoNfTI.