Symfony2 - Dynamic form choices - validation remove

Question

I have a drop down form element. Initially it starts out empty but it is populated with values via javascript after the user has made some interactions. Thats all working

Answer 1

Found a better solution which I posted here: Disable backend validation for choice field in Symfony 2 Type

Old answer:

Just spent a few hours dealing with that problem. This choice - type is really annoying. My solution is similar to yours, maybe a little shorter. Of course it's a hack but what can you do...

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('place', 'choice'); //don't validate that

    //... more form fields

   //before submit remove the field and set the submitted choice as
   //"static" choices to make "ChoiceToValueTransformer" happy
   $builder->addEventListener(FormEvents::PRE_SUBMIT, function (FormEvent $event) {
        $data = $event->getData();
        $form = $event->getForm();
        if ($form->has('place')) {
            $form->remove('place');
        }

        $form->add('place', 'choice', array(
            'choices' => array($data['place']=>'Whatever'),
        ));
    });
}