Validating Symfony3 form with Command not Entity - php

Question

I have prepared a simple application with symfony3.2 and use of DDD (at least I tried). But I have problems validating ProductType form, which uses NewProductCommand instad of Product object.
My form is:
<?php
namespace AdminBundle\Form;
use Shop\Domain\Command\NewProductCommand;
use AppBundle\Form\PriceType;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
use Symfony\Component\Form\Extension\Core\Type\NumberType;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Extension\Core\Type\TextareaType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Form\DataMapperInterface;
use Symfony\Component\Validator\Constraints\Length;
use Symfony\Component\Validator\Constraints\NotBlank;
/**
* Product add form
*
* #package AdminBundle\Form
*/
class ProductType extends AbstractType
{
/**
* Building form
*
* #param FormBuilderInterface $builder
* #param array $options
*/
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add(
'name',
TextType::class,
array(
'required' => true,
'label' => 'Nazwa',
// 'constraints' => [new NotBlank(), new Length(['max' => 255])],
)
)
->add(
'description',
TextareaType::class,
array(
'required' => true,
'label' => 'Opis',
'attr' => [
'rows' => 10
],
// 'constraints' => [new Length(['min' => 100, 'max' => 65000])],
)
)
->add(
'price',
PriceType::class,
array(
'required' => true,
'label' => 'Cena'
)
);
}
/**
* Options configuration
*
* #param OptionsResolver $resolver
*/
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults(
array(
'data_class' => NewProductCommand::class
)
);
}
/**
* Return form name
*
* #return string
*/
public function getName()
{
return 'product';
}
}
And in controller I have:
$command = new NewProductCommand();
$form = $this->createForm(ProductType::class, $command);
$form->handleRequest($request);
if ($form->isSubmitted() && $form->isValid()) {
The validation works when I remove commented constraints, but what I want to achieve is that the form uses my Product class validators.
I think that the problem is that, I pass here NewProductCommand::class, and not the Product::class, so the form doesn't know anything about Product class (which is defined in doctrine orm product mapping: https://github.com/wojto/washop/blob/master/src/Shop/Infrastructure/Repository/Doctrine/config/mapping/Product.orm.yml) and validation, which is in yml too (https://github.com/wojto/washop/blob/master/src/AdminBundle/Resources/config/validation.yml).
Where is the place, I should connect NewProductCommand with Product class so the form can use validation for Product class?
I hope, I make it clear ;) full app code is here: https://github.com/wojto/washop/
Maybe I am doing everything wrong, so I appreciate any help :)