AddPositionLabelSubscriber.php

<?php
namespace NicaStaff\IQAHBundle\Form\EventListener;

use Symfony\Component\Form\Event\DataEvent;
use Symfony\Component\Form\FormFactoryInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Form\FormEvents;
use NicaStaff\IQCoreBundle\Entity;

class AddPositionLabelSubscriber implements EventSubscriberInterface
{
    private $factory;

    public function __construct(FormFactoryInterface $factory)
    {
        $this->factory = $factory;
    }

    public static function getSubscribedEvents()
    {
        // Tells the dispatcher that we want to listen on the form.pre_set_data
        // event and that the preSetData method should be called.
        return array(FormEvents::PRE_SET_DATA => 'preSetData');
    }

    public function preSetData(DataEvent $event)
    {
        $form = $event->getForm();
        $data = $event->getData();  // This is returning null
        
        if (!$data instanceof Entity\DisplayableReportField) {
            throw new \Exception(
                'AddPositionLabelSubscriber::data must be an instance of Entity\DisplayableReportField'
            );
        } elseif (!$data->getField() instanceof Entity\Field) {
            throw new \Exception(
                'AddPositionLabelSubscriber::data::Field must be an instance of Entity\Field'
            );
        }

        $field = $data->getField();

        $form->add($this->factory->createNamed('text', 'position', null, array('label' => $field->getName())));
    }
}

DisplayableReportFieldType.php

<?php

namespace NicaStaff\IQAHBundle\Form;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilder;
use NicaStaff\IQCoreBundle\Repo\FieldRepo;
use NicaStaff\IQCoreBundle\Entity;
use NicaStaff\IQAHBundle\Form\EventListener\AddPositionLabelSubscriber;
use Symfony\Component\Form\Event\DataEvent;
use Symfony\Component\Form\FormEvents;

class DisplayableReportFieldType extends AbstractType
{
    public function buildForm(FormBuilder $builder, array $options)
    {
        switch ($options['mode']) {
            case 'step2':
                $subscriber = new AddPositionLabelSubscriber($builder->getFormFactory());
                $builder->addEventSubscriber($subscriber);
                /*
                $builder->addEventListener(FormEvents::PRE_SET_DATA, function (DataEvent $event) use ($builder)
                {
                    $form = $event->getForm();
                    $data = $event->getData();

                    // Check we're looking at the right data/form
                    if ($data instanceof Entity\DisplayableReportField)
                    {
                        $label = $data->getField()->getName();

                        $form->add($builder->getFormFactory()->createNamed(
                            'text',
                            'position',
                            null,
                            array('label' => $label)
                        ));
                    }
                });
                $builder->add('position'); // this is required in order to show 'position' widget properly
                */
  
                break;

            case 'step3':
                $builder->addEventListener(FormEvents::PRE_SET_DATA, function (DataEvent $event) use ($builder)
                {
                    $form = $event->getForm();
                    $data = $event->getData();

                    /* Check we're looking at the right data/form */
                    if ($data instanceof Entity\DisplayableReportField)
                    {
                        $label = $data->getField()->getName();

                        $form->add($builder->getFormFactory()->createNamed(
                            'text',
                            'label',
                            null,
                            array('label' => $label)
                        ));
                    }
                });
                $builder->add('label'); // this is required in order to show 'label' widget properly
                

        }
            
    }

    public function getDefaultOptions(array $options)
    {
        return array(
            'data_class' => 'NicaStaff\IQCoreBundle\Entity\DisplayableReportField',
            'validation_groups' => array('default'),
            'table' => null,
            'mode' => 'default',
        );
    }

    public function getName()
    {
        return 'nicastaff_iqahbundle_displayreportfieldtype';
    }
}