Login form usando Zend_Dojo_Form

Login.php

<?php

class Application_Form_Login extends Zend_Dojo_Form
{

    public function init()
    {
        $this->setName('Login');

        //elementos do Dojo
        $this->addElement(
            'ValidationTextBox',
            'username',
            array(
                'label'          => 'Login',
                'required'       => true,
                'regExp'         => '[\w]+',
                'invalidMessage' => 'Não pode existir espaços.',
            )
        );
        
        $this->addElement(
            'PasswordTextBox',
            'password',
            array(
                'label'          => 'Senha',
                'required'       => true,
                'trim'           => true,
                'lowercase'      => true,
                'regExp'         => '^[a-z0-9]{3,}$',
                'invalidMessage' => 'Senha inválida. Precisa ter no mínimo 3 caracteres',
            )
        );
        $this->addElement(
            'SubmitButton',
            'enviar',
            array(
                'required'   => false,
                'ignore'     => true,
                'label'      => 'Entrar!',
            )
        );
        
        //action e method
        $this->setAction('/auth/index')->setMethod('post');
    }
}