angularjs - select2 - tagging with objects

http://angularjs.org/

HTML

<link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/2.2.1/css/bootstrap.css">
<link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/select2/3.4.0/select2.css">
<script src="http://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/2.2.1/bootstrap.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.0.5/angular.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/select2/3.4.0/select2.min.js"></script>
<div style="border: 1px solid red;margin-bottom:10px;"> angular-ui + select2
    <div ng-controller="MyCtrl">
        <input type="text"  ui-select2="tagAllOptions" ng-model="tagsSelection" style="width:300px;" />
        <pre>tagSelection: {{tagsSelection | json}}</pre>
    </div>
</div>

JavaScript

/**
 * Enhanced Select2 Dropmenus
 *
 * @AJAX Mode - When in this mode, your value will be an object (or array of objects) of the data used by Select2
 *     This change is so that you do not have to do an additional query yourself on top of Select2's own query
 * @params [options] {object} The configuration options passed to $.fn.select2(). Refer to the documentation
 */
angular.module('ui.select2', []).value('uiSelect2Config', {}).directive('uiSelect2', ['uiSelect2Config', '$timeout', function (uiSelect2Config, $timeout) {
  var options = {};
  if (uiSelect2Config) {
    angular.extend(options, uiSelect2Config);
  }
  return {
    require: 'ngModel',
    priority: 1,
    compile: function (tElm, tAttrs) {
      var watch,
        repeatOption,
        repeatAttr,
        isSelect = tElm.is('select'),
        isMultiple = angular.isDefined(tAttrs.multiple);

      // Enable watching of the options dataset if in use
      if (tElm.is('select')) {
        repeatOption = tElm.find( 'optgroup[ng-repeat], optgroup[data-ng-repeat], option[ng-repeat], option[data-ng-repeat]');

        if (repeatOption.length) {
          repeatAttr = repeatOption.attr('ng-repeat') || repeatOption.attr('data-ng-repeat');
          watch = jQuery.trim(repeatAttr.split('|')[0]).split(' ').pop();
        }
      }

      return function (scope, elm, attrs, controller) {
        // instance-specific options
        var opts = angular.extend({}, options, scope.$eval(attrs.uiSelect2));

        /*
        Convert from Select2 view-model to Angular view-model.
        */
        var convertToAngularModel = function(select2_data) {
          var model;
          if (opts.simple_tags) {
            model = [];
            angular.forEach(select2_data, function(value, index) {
              model.push(value.id);
            });
          } else {
            model = select2_data;
          }
          return model;
        };

        /*
        Convert from Angular view-model to Select2...