class BirthPlaceType extends AbstractType
{

    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('postal_code', TextType::class, [
                'label' => 'Postal code',
                'property_path' => 'birthplace.postalCode',
                'required' => true,
                'constraints' => [
                    new NotBlank(),
                    new Regex([
                        'pattern' => '/^(?:[0-8]\d|9[0-8])\d{3}$/',
                        'message' => 'validator.address.postal_code'
                    ])
                ]
            ])),
//[...]

class RegistrationType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('birthplace', BirthPlaceType::class, ['data_class' => UserProfile::class])
//[...]

class RegistrationController extends AbstractController
{
    public function form(Request $request)
    {
        $form = $this->createForm(RegistrationType::class, new UserProfile());
        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
            //[...]
        }

        return $this->render('registration/form.html.twig', ['form' => $form->createView()]);
    }
}