ajax request with json in yii

Ajax request using Yii ajaxButton
json mixing format like dot,associative array etc

In view.php
--------------
<?php echo CHtml::ajaxButton('User List',CController::createUrl('user/active'), array(
        'type' => 'POST',
        'dataType'=>'json',
        'data'=>"js:callData()", Call JS Function OR Give datastring
        'url'=> 'user/active',
        'success'=>"function(response){
            alert(response);
            if(response!=''){
                alert(response.url);
                if(response['message']!=''){
                    alert(response['message']);
                }
                if(response['url']!=''){
                    window.location=response['url'];    
                }
            }
           }",
        ),array('id'=>'activebtn')
    );    
?> 

In Controller .php
------------------
 public function actionactive() {
   $returnmessage['message']=$successmessage;
   $returnmessage['url']="url";
    echo json_encode($returnmessage);   
   }