title: AngularJS Multiselect checkbox dropdown Issue
body: <p>I have a pop-up with multi-select drop down. </p>
  
  <p>Multi-Select Dropdown Code</p>
  
  <pre><code>&lt;select name="edit_tags" class="form-control" id="advisor_article_tagsx" multiple="" 
     required ng-model="article_selected" ng-options="article_service as article_service.name for article_service in article_services"&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>There is an array <code>article_services</code> which is used in multi-select, I am fetching this array from below code.</p>
  
  <pre><code>$http.get(url + 'service_provided').
       then(function (response) {
           $scope.article_services = response.data.service_provided;
           //$scope.article_selected = [$scope.article_services[0], $scope.article_services[1]];
  });
  </code></pre>
  
  <p>Now I want that when I click on Edit Button with <code>ng-click="advisor_article_edit()"</code> to open pop-up, my multi-select checkbox comes with some selection.
  I want that Select must be work in below function but unfortunately it doesn't work. </p>
  
  <pre><code>$scope.advisor_article_edit = function () {
          // I need selection work from here. But it doesn't.
          $scope.article_selected = [$scope.article_services[3]];
   }
  </code></pre>