Zend_Form disable populate before isValid()

Im not able to disable populating values in Zend_Form .

I have my own form class. With hidden token element where I would like to dynamicaly setup random value every time the form is called (or reposted). I thought that setValue will make the job.

class MY_Form_Test extends Zend_Form {
    public function init() {
    ...

    $this->addElement('hidden', 'token');
    $this->getElement('token')->setValue(uniqid('',true));
    ... 
}

BUT: When I have simple controller like this. Zend automate populating old hidden values except to generate new one.

$form = new JC_Form_Test();
if($form->isValid($_POST)){
   // Action ... 
}
else{
   // Error
}

SOLUTION: The only solution I found is to call setValue in Controler AND AFTER isValid method. eg. in Error block.

QUESTION: Is there any way to setup element va开发者_如何学运维lues directly in form class OR disable populate values in form class or before isValid() is called?

---

I think it's the best way to do it.

I work much with Zend Framework and have my own library for overwrite some Zend classes.

It's not bad to change something, but don't do it directly within Zend Framework

---

SECOND SOLUTION: Second solution I found is to overload isValid() method in Form class. Like this. Then I dont need to put setValue() into every Controller.

class MY_Form_Test extends Zend_Form {

    ...

    public function isValid($data){
    // Propagate values
    $valid = parent::isValid($data);

    $this->getElement('token')->setValue(uniqid('',true));

    return $valid;
}

Are there any other solution eg. some element option to do this job more simple?