双重选择angular-js ajax

I'm trying to retrieve the first selected value and then run an ajax call to get the 2nd set of data based on the first selected selected value.

HTML:

<label class="item item-input item-select">
  <div class="input-label">
   Select First:
   </div>

   <select>
    <option  ng-repeat="object in objects" value="object.ID">{{object.value}}</option>
   </select>
</label>

<label class="item item-input item-select">
  <div class="input-label">
   Select 2nd:
  </div>

  <select>
  <option></option>
  </select>
</label>

Controller Side:

...
dataFactory.getRequestObject(ID).then(function(resp2){
      console.log("Getting data to populate select list!");
      console.log(resp2.data);
      $scope.objects= resp2.data;

    }, function(err){
        console.error('ERROR', err);
    });

Where getRequestObject(ID) is my function which calls my webservice.

I'm able to get my first set of data, I would like to get the "value" of the first and invoke the retrieving of the 2nd select list of data. How would I go around doing it?

$.getJson(url, param, function(data) {
  $scope.array1 = data.array;
});
$scope.onchange = function() {
  //ng-model will store its value into $scope
  var selectValue1 = $scope.selectValue1;
  
  $.getJson(url2, param2, function(data) {
    $scope.array2 = data.array;
  });
};

<select ng-module="selectValue1" ng-options="label for value in array1" ng-change="onchange()"></select>
<select ng-module="selectValue2" ng-options="label for value in array2"></select>

use $watch to detect selectValue change will also work

</div>