How can I get the value of a Zend_Form in zend project

I have a Zend_Form called login.php in my zend project.

In controller I have

$request = $this->getRequest();
        $request->setMethod('post')
                ->setPost(array(
                    'username' => 'admin',
                    'password' => '111111',
                ));
        $this->dispatch(开发者_如何学C'/en/auth/login');
        $values = $form->getValues();

I wonder how can I get values from this form? $form->getValues() will return a array? and how to get the username and password form it?

if($this->getRequest()->isPost())
{
   if($form->isValid($this->getRequest()->getPost())
   {
      //Here is form->getValue() enabled
      echo $form->getValue('elementName');
   }
}

getValue isn't available unti the form is valid

another option:

$values = $form->getValues();

$username = $values['username'];
$password = $values['password'];

and if are using:

$form->setElementBelongsTo(´login');

then you need to call the ElementBelongsTo string first.

$values = $form->getValues();

$username = $values['login']['username'];
$password = $values['login']['password'];