AngularJS - Add Select model option in Json string
<p><strong>HTML</strong></p>

<pre><code>&lt;form ng-submit="exportVideoForm()"&gt;
    &lt;input type="text" class="form-control" ng-model="exportvideo.exportName" required&gt;

    &lt;input type="text" class="form-control" ng-model="exportvideo.description" required&gt;

    &lt;select class="form-control" name="selectposition" id="selectposition" 
          ng-options="position.name for position in data.waterMarkImgPosition track by position.id"
          ng-model="data.selectedPosition"
          ng-change="changePosition(data.selectedPosition)"
          required&gt;
    &lt;option ng-show="false" value=""&gt;Please Select&lt;/option&gt;
    &lt;/select&gt;
&lt;/form&gt;
</code></pre>

<p><strong>Ctrl</strong></p>

<pre><code>$scope.exportVideoForm = function() {

        $scope.data.selectedPosition.id = 'lowerLeft';
        $scope.exportvideo = $scope.exportvideo.push($scope.data.selectedPosition.id); //push watermark position in json string
        $scope.exportVideoJson = angular.toJson($scope.exportvideo); //convert to json

};
</code></pre>

<p><strong>Output</strong></p>

<pre><code>console.log($scope.exportVideoJson) = {"exportName":"myname","description":"mydesc"}
</code></pre>

<p>When I try to <code>concat/push</code> position.id, it throws exception
<strong>Error: $scope.exportvideo.push is not a function</strong></p>

<p>How do I add position.id value to existing json string ?</p>