php - Generating dynamic dropdown list in Yii? -

i need generate second dropdownlist based on choice of first.

view in _form.php:

<?php  echo chtml::dropdownlist('category_id','', category::allcategory(),      array(      'ajax' => array(      'type'=>'post', //request type      'url'=>ccontroller::createurl('subcategory/dynamicsubcategories'), //url call.      //style: ccontroller::createurl('currentcontroller/methodtocall')      'update'=>'#subcategory_id', //selector update      //'data'=>'js:javascript statement'      //leave out data key pass form values through      )));       //empty since filled other dropdown      echo chtml::dropdownlist('subcategory_id','', array()); ?> 

also created controler: subcategorycontroller.php

public function actiondynamicsubcategories() {         $data = subcategory::model()->findall('category_id=:category_id',                  array(':category_id' => (int)$_post['category_id']));          $data = chtml::listdata($data, 'id', 'title');         foreach ($data $value => $name) {             echo chtml::tag('option', array('value' => $value), chtml::encode($name), true);         }     } 

i registered rules performance of action in same controler: function accessrules

array('allow', // deny users             'actions' => array('dynamicsubcategories'),             'users' => array('@'),         ), 

the table 'category' has structure: id, title, position , category::allcategory() return:

return chtml::listdata($models, 'id', 'title'); 

the table 'subcategory' has structure: id, title, category_id.

unfortunately, inquiry carried out in second dropdownlist displayed nothing, prompt made not correctly?

result:

look @ http://www.yiiframework.com/doc/api/1.1/chtml#dropdownlist-detail, no ajax params, htmloptions. have organize ajax on change event of select#category_id:

like that:

<?php echo chtml::dropdownlist('category_id','', category::allcategory(), array('onchange' => 'getsubcategory(this.value)')); ?> <script>function getsubcategory(val) { $.ajax({      type :'post', //request type      url : '<?php echo ccontroller::createurl('subcategory/dynamicsubcategories')?>',      success : function(data) {          $('#subcategory_id').html(data);      } };</script>