Zend Framework Form Validation Example

I am beginner in Zend Framework 3 and I want to hear your opinions about code that I wrote. I don't know how exactly I can connect forms, and validators together that the code will be quite nice and readable.

So I wait for yours advices....what I need to correct, what doesn't have sense, what could be done better...etc...

/register method

 public function registerAction()
    {
        $form = $this->form;
        $viewModel = new ViewModel(['form' => $form]);
        $prg = $this->prg('users', false);


        if ($prg instanceof \Zend\Http\PhpEnvironment\Response)
            return $prg;

        elseif ($prg === false)
            return $viewModel;


        $loginExistsValidator = new NoRecordExists(
            [
                'table' => 'users',
                'field' => 'login',
                'adapter' => $this->command->getAdapter()
            ]
        );
        $loginExistsValidator->setMessage('Istnieje już użytkownik o podanym loginie');

        $emailExistsValidator = new NoRecordExists(
            [
                'table' => 'users',
                'field' => 'email',
                'adapter' => $this->command->getAdapter()
            ]
        );
        $emailExistsValidator->setMessage('Ten email jest już zajęty...');

        $form->setInputFilter(new UsersFilter());
        $form->getInputFilter()->get('login')->getValidatorChain()->attach($loginExistsValidator);
        $form->getInputFilter()->get('email')->getValidatorChain()->attach($emailExistsValidator);
        $form->setData($prg);

        if (!$form->isValid())
            return $viewModel;

        $users = $this->command->addUser($form->getData());

        $viewModel->setTemplate('users/register/registerSukcesfull');

        return ['users' => $users];
    }

/usersFilter

    <?php
/**
 * Created by PhpStorm.
 * User: Patryk
 * Date: 2016-10-09
 * Time: 12:19
 */namespace Users\Filters;



use Users\Services\RegisterServices;
use Zend\Filter\Callback;
use Zend\Filter\StringTrim;
use Zend\InputFilter\InputFilter;
use Zend\Validator\Db\NoRecordExists;
use Zend\Validator\Db\RecordExists;
use Zend\Validator\EmailAddress;
use Zend\Validator\Regex;
use Zend\Validator\StringLength;

class UsersFilter extends InputFilter
{
    public function __construct()
    {
        $this->add([
                'name' => 'login',
                'required' => true,
                'filters' => [
                    [
                        'name' => StringTrim::class
                    ]
                ],

                'validators' => [

                    [
                        'name' => StringLength::class,
                        'options' => [
                            'min' => 5
                        ]
                    ],



                ],
            ]

        );
        $this->add([
                'name' => 'password',
                'required' => true,
                'validators' => [

                    [
                        'name' => StringLength::class,
                        'options' => [
                            'min' => 12
                        ]
                    ],
                ],
            ]

        );

        $this->add([
                'name' => 'email',
                'required' => true,
                'validators' => [
                    [
                        'name' => EmailAddress::class,
                        'options' =>
                        [
                            'domains' => true
                        ]
                    ]
                ]

        ]);
    }


}