Angular JS更改时显示/隐藏事件

我有一个多重下拉列表,我想根据下拉列表上的更改事件来显示/隐藏。它是嵌套元素下拉列表。

http://jsfiddle.net/U3pVM/60518/

angular.module('myApp', []).controller('CEventCtrl', ['$rootScope', '$scope',
    function($rootScope, $scope) {
        var $this = this;

        $this.bUOptions = '[{"id":"bu_0","options":[{"id":"","name":"Not Selected"},{"id":6,"name":"Bhumi1"},{"id":12,"name":"*Sales*"},{"id":17,"name":"*Support*"}],"label":"Department","showif":null},{"id":"bu_12","options":[{"id":"","name":"Not Selected"},{"id":13,"name":"AU Sales"},{"id":14,"name":"USA Sales"}],"label":"Section","showif":"bu_0=12"},{"id":"bu_14","options":[{"id":"","name":"Not Selected"},{"id":16,"name":"USA East Sales"},{"id":15,"name":"USA West Sales"}],"label":"Region","showif":"bu_12=14&&bu_0=12"},{"id":"bu_17","options":[{"id":"","name":"Not Selected"},{"id":18,"name":"AU Support"},{"id":19,"name":"UK Support"}],"label":"Section","showif":"bu_0=17"}]';

        $scope.bUn = {};
        this.count = 0;
        this.isBUChildElement = function(value, key) {
            this.bU = {};
            bU = $this.bUOptions;console.log(bU);
            if (value !== '' & typeof bU[key] == 'undefined') {
                if (!$scope.bUn[key]) {
                    $scope.bUn[key] = false;
                }
            }
            else {
                $scope.bUn[key] = true;
            };
            return $scope.bUn[key];
        }

        this.getBUChild = function(selectedValue, showif,selectedElement){
            var splitKey = selectedElement.split('_')[0];
            angular.forEach(bUn, function(value, key){
                if(splitKey+'_'+selectedValue !== key){
                    bUn[key] = false;
                }
                bUn[splitKey+'_'+selectedValue] = true;
            });
            if (showif !=='') {
                if (showif.indexOf("&&") === -1) {
                    var splitShowif = showif.split('=');
                    console.log('');
                    console.log(splitKey+'_'+splitShowif[1]);
                    bUn[splitKey+'_'+splitShowif[1]] = true;
                } 
                else {
                    var splitShowif = showif.split('&&');
                    angular.forEach(splitShowif, function(value, key) {
                        var splitShowifParts = value.split('=');
                        console.log('');
                        console.log(splitKey+'_'+splitShowifParts[1]);
                        bUn[splitKey+'_'+splitShowifParts[1]] = true; 
                    });
                }
            }

          bUn[selectedElement] = true;
      }
    }
]);

但不知何故,它多次呼叫,并没有妥善隐藏。