Symfony Forms: Adding a CallbackTransformer to a field that is added in an EventListener

Question

I have a somewhat complex form and am struggling with adding a ModelTransformer to a dynamically added field.

First I have a basic form with some fields and one CollectionType field that includes a custom Type:

class FilterType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        // adding some other fields here ...

        $builder->add('conditions', Type\CollectionType::class, [
            'entry_type' => FilterRowType::class,
            'allow_add' => true,
            'prototype' => true,
            'allow_delete' => true,
            'entry_options' => ['label' => false],
        ]);
    }
}

The FilterRowType consists of several fields that are depending on each other.
First the user has to select an option from a dropdown and then another field is added whose type and options depend on the selected value of the first field.
The second field could be TextType or NumberType or even ChoiceType with its choices again depending on the first field.
Finally I need to add a CallbackTransformer to this second field.
So here is what I currently have (widely stripped of stuff I think is not important for this question):

class FilterRowType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->add('attribute', Type\ChoiceType::class, [
            'choices' => $this->getAttributeChoices(),
        ]);
        $builder->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) use ($builder) {
            $this->addDynamicInputs($event, $builder);
        });
        $builder->addEventListener(FormEvents::PRE_SUBMIT, function (FormEvent $event) use ($builder) {
            $this->addDynamicInputs($event, $builder);
        });
    }

    public function addDynamicInputs(FormEvent $event, FormBuilderInterface $builder)
    {
        $form = $event->getForm();
        $data = $event->getData();

        // adding some other fields ...

        $valueConfig = $this->getValueConfig($data['attribute']);
        $form->add('value', $valueConfig['type'], $valueConfig['options']);
        $valueConfig['options']['auto_initialize'] = false;
        $form->add(
            $builder->create('value', $valueConfig['type'], $valueConfig['options'])
                ->addModelTransformer($this->getCallbackTransformer ())
                ->getForm()
        );
    }
}

And this is actually working ! :)

BUT:
As you might already have spotted I am actually adding the 'value' field twice here.
This happened by accident as I added the CallbackTransformer later and forgot to delete the original line.
The problem is that if I now remove the original line $form->add('value', $valueConfig['type'], $valueConfig['options']); I run into an exception:

Neither the property "value" nor one of the methods "value()", "getvalue()"/"isvalue()"/"hasvalue()" or "__call()" exist and have public access in class "Symfony\Component\Form\FormView".

Probably because I set $valueConfig['options']['auto_initialize'] = false; for the new creation of the field?
But if I remove that line I run into a different error:

Automatic initialization is only supported on root forms. You should set the "auto_initialize" option to false on the field "value"

Of course I could leave everything as it is with adding the 'value' field twice.
But that seems a very fishy solution to me and I am afraid that it might have some unforeseen consequences even if currently everything seems to work fine.

So can maybe someone with more insight into symfony forms enlighten me?
Are there possible problems with my 'solution' ?
Is there a better/proper way of doing what I am trying to do?

user_1750964 · Answer

I had the same case today. Here is what I did :

Create an extension :

namespace App\Form\Extension;

use Symfony\Component\Form\AbstractTypeExtension;
use Symfony\Component\Form\Extension\Core\Type\FormType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\OptionsResolver\OptionsResolver;

class ModelTransformerExtension extends AbstractTypeExtension {

    public static function getExtendedTypes(): iterable {
        return [FormType::class];
    }

    public function buildForm(FormBuilderInterface $builder, array $options) {
        parent::buildForm($builder, $options);
        if (isset($options['model_transformer'])) {
            $builder->addModelTransformer($options['model_transformer']);
        }
    }

    public function configureOptions(OptionsResolver $resolver) {
        parent::configureOptions($resolver);
        $resolver->setDefaults(array('model_transformer' => null));
    }
}

Use it in your form field options :

$builder->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) {
   $form = $event->getForm();
   $form->add('fieldName', $TextType::class, [
      'model_transformer' => // Your transformer here
   ]);
});

Symfony Forms: Adding a CallbackTransformer to a field that is added in an EventListener

1 Answers