如何在Collection表单类型上应用验证规则？

For example we have two entities one Car and one Person, when we modify PersonType like below:

$builder
    ->add('email')
    ->add('cars','collection',array(
        'type' => new CarType(),
        'allow_add' => true,
        'allow_delete' => true,
        'by_reference' => false,
    ))
    ->add('submit','submit')

and have following validation rules for Car entity:

Mtm\AppBundle\Entity\Car:
properties:
  file:
    - File:
      maxSize: 100k
      mimeTypes: [application/pdf, application/x-pdf]
      mimeTypesMessage: Please upload a valid PDF

Validation rules doesn't apply on form, it just makes html5 validation on it, not server side validation.

Any idea how should I do that?

Set cascade_validation property to true:

$builder
    ->add('email')
    ->add('cars','collection',array(
        'type' => new CarType(),
        'allow_add' => true,
        'allow_delete' => true,
        'by_reference' => false,
        'cascade_validation' => true
    ))
    ->add('submit','submit')

http://symfony.com/doc/current/reference/forms/types/collection.html#cascade-validation

Working solution is below:

/**
 * @param OptionsResolverInterface $resolver
 */
public function setDefaultOptions(OptionsResolverInterface $resolver)
{
    $resolver->setDefaults(array(
        'data_class' => 'Mtm\AppBundle\Entity\Person',
        'cascade_validation' => true,
    ));
}

I had to add it in defaultOptions.

Thx to dmnptr for providing way to find the right answer.