Symfony2 form events and model transformers

Question

I\'m getting tied in knots trying to wrestle with Symfony2\'s form builders, events and transformers... hopefully somebody here is more experienced and can help out!

Answer 1

Your listener looks (almost :) ) ok.

Just use PRE_SUBMIT. In that case, $event->getData() will be the raw form data (an array) that is sent. $selectedFoo will potentailly contain "other".

If it is the case, you will replace the "short" 'choice' field with a full one, by using formFactory in the listener.

$builder->addEventListener(FormEvents::PRE_SUBMIT, function(FormEvent $event) {
    $data = $event->getData();
    if (empty($data['linkedFoo']) || $data['linkedFoo'] !== 'other') {
        return;
    }

    // now we know user choose "other"
    // so we'll change the "linkedFoo" field with a "fulllist"


    $event->getForm()->add('linkedFoo', 'choice', array(
        'choices' => $fullList, // $em->getRepository('Foo')->getFullList() ?
    ));
    $event->getForm()->get('linkedFoo')->getConfig()->addModelTransformer(new FooTransformer);
});

You asked so much questions I don't know where to start.

Concerning dataTransformers: until you want to transform raw data into a different representation ("2013-01-01" -> new DateTime("2013-01-01")), then you don't need transformers.