Symfony2 Forms: dynamic "NotBlank"-constraints

StreetAddressType.php

<?php

namespace Ormigo\Bundle\OrmigoBundle\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

use Ormigo\Bundle\OrmigoBundle\Form\DataTransformer\StreetAddressModelTransformer;
use Ormigo\Bundle\OrmigoBundle\Form\Validator\StreetAddressValidator;

use Symfony\Component\Validator\Constraints\NotBlank;
use Symfony\Component\Validator\Constraints\Regex;

class StreetAddressType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $constraints = array(
            'street' => array(),
            'zipcode' => array(
                new Regex(array(
                    'pattern' => '/\d{5}/',
                    'message' => 'street_address.zipcode.invalid',
                )),
            ),
            'city' => array(),
        );

        if ($options['required']) {
            $constraints['street'] = array_merge(array(
                new NotBlank(array(
                    'message' => 'street_address.street.required',
                )),
            ), $constraints['street']);

            $constraints['zipcode'] = array_merge(array(
                new NotBlank(array(
                    'message' => 'street_address.zipcode.required',
                )),
            ), $constraints['zipcode']);

            $constraints['city'] = array_merge(array(
                new NotBlank(array(
                    'message' => 'street_address.city.required',
                )),
            ), $constraints['city']);
        }

        $builder
            ->add('street', 'text', array(
                'label' => 'label.street',
                'constraints' => $constraints['street'],
                'autocomplete' => 'street-address',
            ))
            ->add('zipcode', 'text', array(
                'label' => 'label.zipcode',
                'constraints' => $constraints['zipcode'],
                'attr' => array(
                    'pattern' => '\d{5}',
                ),
                'autocomplete' => 'postal-code',
            ))
            ->add('city', 'text', array(
                'label' => 'label.city',
                'constraints' => $constraints['city'],
                'autocomplete' => 'city',
            ))
        ;

        $builder->addModelTransformer(new StreetAddressModelTransformer());
        $builder->addEventSubscriber(new StreetAddressValidator());
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'data_class' => 'Ormigo\Bundle\OrmigoBundle\Form\Model\Address',
            'error_bubbling' => false,
            'invalid_message' => 'street_address.invalid',
        ));
    }

    public function getName()
    {
        return 'street_address';
    }
}

Nice, thanks for the inspiration 👍