Yii实现的多级联动下拉菜单

<?php echo CHtml::activeDropDownList($model,'zmg_id',MemGroup::model()->getMemGroup(),array(    'class'=>'s_ipt w_120',    'empty'=>'请选择会员组',    'ajax' =>array(          'type'=>'GET',          'url'=>CController::createUrl('cmpTemplates/getMemType'),          'update'=>'#CmpTemplates_zmg_ids',          'data'=>array('mid'=>"js:this.value")          ),    ))?><?php echo $form->dropDownList($model,'zmg_ids',array(),array('class'=>'s_ipt w_120','empty'=>'选择会员等级'))?>

/** * 获取会员组,对应的会员等级，用于下拉菜单 */public function actionGetMemType($mid=0){  $criteria=new CDbCriteria;  $criteria->compare('zmg_id',$mid);  $memType = MemType::model()->findAll($criteria);  $name = '选择会员等级';  echo CHtml::tag('option', array('value'=>0), $name, true);  foreach($memType as $val) {    echo CHtml::tag('option', array('value'=>$val->zmt_id),CHtml::encode($val->zmt_title),true);  }}

/** 取会员组信息*/public function getMemGroup($type=null){  if($type==null){    $criteria=new CDbCriteria;    $criteria->compare('type','1');    $memGroup = MemGroup::model()->findAll($criteria);    return CHtml::listData($memGroup,'zmg_id','zmg_title');  }else{    $level = $this->getMemGroup();    if(array_key_exists($type,$level)){      return $level[$type];    }  }}