Doctrine password hash after regexp validate

I have a problem during save password on database. I have password field with complex regexp validator (minlenght + special chars + alphanumerics). After send form, password value is checked by validator. After that (if value is valid) I would like hash password and finally save this value, but regexp validator still validate field and return error.

How can i disable validator before finally save ha开发者_开发技巧shed value?

Sorry for my english!

Code:

On user model:

 public function setTableDefinition()
 {
     $this->hasColumn('password', 'string', 32, array ('notnull'=>true, 'minlength'=>8, 'regexp'=> '/^.*(?=.{8,})(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%^&+=]).*$/'));
     .......
 }

 public function setUp()
 {
        $this->addListener(new userChangeListener());
 }

On listener:

class userChangeListener extends Doctrine_Record_Listener
{
    public function postValidate(Doctrine_Event $event)
    {
        $invoker = $event->getInvoker();
        $invoker->password = md5($invoker->password);
    }   
}