Angularjs如何根据一个select的值去设置另一个select的值

<div ng-controller="mySelectController">
<select ng-model="myField" ng-options="Field.label for Field in names" 
ng-change="mySelectControllerChange()">
<option value=''>{{'SELECT.LABEL.VXI.CUSTOM.SELECT' | translate}}</option>
</select>
</div>
 <div ng-controller="myRelationController">
<select ng-model="myRelation" ng-options="relation.name for relation in relationList" >
<option value=''>{{'SELECT.LABEL.VXI.CUSTOM.SELECT' | translate}}</option>
</select>
</div>

var mySelectController=['$scope', '$http', '$rootScope', function($scope, $http, $rootScope) {
 
 //$http的method可以是get/delete/head/jsonp/post/put
 //$http服务快捷的get请求
 //alert('root=='+ACTIVITI.CONFIG.contextRoot);//对应/activiti-explorer/service
 $http({
 method:'PUT',
 url:ACTIVITI.CONFIG.contextRoot +'/getFormFieldList'
 })
 .success(
 function(data,status,headers,config){
 //成功加载
   $scope.names=data;
 })
 .error(
 
 function(data,status,headers,config){
 //处理错误
 //do nothing
 }
 );
 //change
 $scope.mySelectControllerChange=function(){
 var app=angular.module('activitiModeler',[]);
 if($scope.myField.optionGroupId!=null && $scope.myField.optionGroupId!=''){
 //有optionGroup
 console.log('if');
 $rootScope.relationList = [{id:0,name:'等于'},{id:1,name:'不等于'},{id:2,name:'包含'}];
 }else{
 //没有optionGroup
 console.log('else');
 $rootScope.relationList = [{id:0,name:'等于'},{id:3,name:'大于'},{id:4,name:'小于'},{id:5,name:'小于等于'},{id:6,name:'大于等于'},{id:2,name:'包含'}];
 }
 
 }
 
}
];

//change
 $scope.mySelectControllerChange=function(){
 var data=null;
 if(null==$scope.myColumnSelectModel){
 data={
  pa:'',
  pb:''
 };
 }else{
 data={
  pa:$scope.myColumnSelectModel,
  pb:$scope.myColumnSelectModel.optionGroupId
 };
 }
 $scope.$emit('to_myParentController_on_myColumnSelectModel_change',data);
 }
 
/*myParentController*/
angular.module('activitiModeler').controller('myParentController',['$rootScope', '$scope', '$http', '$timeout','$window', function ($rootScope, $scope, $http, $timeout,$window) {
 //选择字段下拉列表，触发关系符下拉
 $scope.$on('to_myParentController_on_myColumnSelectModel_change',function(event,data){
 $scope.$broadcast('to_myRelationController_on_myColumnSelectModel_change',data);
 });
 
 
}]);
 
/*关系符*/
angular.module('activitiModeler').controller('myRelationController',['$rootScope', '$scope', '$http', '$timeout','$window', function ($rootScope, $scope, $http, $timeout,$window) {
 $scope.myRelationDisableVar=true;
 $scope.objDisableTrue=true;//加上灰背景
 //接收事件-根据字段显示下拉
 $scope.$on('to_myRelationController_on_myColumnSelectModel_change',function(event,data){
 if(data.pa!=''){
 $scope.myRelationDisableVar=false;
 $scope.objDisableTrue=false;//去掉灰背景
 if(data.pb!=null && data.pb!=''){
 //有optionGroup
 $scope.relationList = [{id:0,name:'等于'},{id:1,name:'不等于'},{id:2,name:'包含'}];
 }else{
 //没有optionGroup
 $scope.relationList = [{id:0,name:'等于'},{id:3,name:'大于'},{id:4,name:'小于'},{id:5,name:'小于等于'},{id:6,name:'大于等于'},{id:2,name:'包含'}];
 }
 }else{
 $scope.relationList=null;
 $scope.myRelationDisableVar=true;
 $scope.objDisableTrue=true;//加上灰背景
 }
 
 });
 
}]);