AJAX

		<?php
		echo $form->dropDownList($model, 'service_id', CHtml::listData(Service::model()->findAll(array('order'=>'description,code')),'id','description'),
				array(
					'prompt' => 'Select Service ...',
					'ajax' => array(
						'type'=>'POST', //request type
						'url'=>CController::createUrl('updatePrice'), //url to call.
						'data'=>array('service_id'=>'js:this.value'),
						'dataType'=>'json',
						'success'=>'js:function(data) {
							var price="#'.CHtml::activeId($model, 'price').'";
							$("#price_id").value(data.price);
						}',
					)
				)
			);
		?>


<?php  // in the ServiceContoller.php of above

	public function actionUpdatePrice() {
		if (Yii::app()->request->isAjaxRequest) {
			$service=Service::model()->findByPk($_POST['service_id']);
			if (isset($service))
				echo CJSON::encode(array(
					'price'=>$service->defaultPrice,
				));
			else
				echo CJSON::encode(array(
					'price'=>0.00,
				));
		}
	}


?>