在Zend Framework中提交后重定向到上一页

I know this has been answered somewhat but I can't seem to get it work for my specific config. Apologies if this is deemed a duplicate.

I have a cart built in Zend with a button that points to a login page via:

if(!$session->id)
{
  header('Location:'.$fullurl.'login');
}

The button is inside a form by itself. I've tried Arne's suggestion below with no dice. Form code:

<form name="" action="' . $fullurl . 'continue" method="post">
   <input type="submit" name="topay" value="CONTINUE SHOPPING" />
</form>';

How do I get and redirect to the last page visited rather than going to /login?

I've tried doing the old HTTP_REFERER method but couldn't get it to work in Zend.. I understand there's a different method in Zend but can't get it to work from various answers here and here.

Any help is greatly appreciated.

I would use this:

$url = Zend_Controller_Front::getInstance()->getRequest()->getRequestUri();
$session = new Zend_Session_Namespace('Namespace');
$session->redirect = $url;

// redirect
$this->_redirect($url, array('prependBase' => false));