Symfony 4: In context of edit (not creation) allow the fields to be partialy modified (single fields could be submitted, the rest ignored)

PageType.php

<?php declare(strict_types = 1);

namespace App\Core\Form\Type;

use App\Core\Service\Content\TextUtils;
use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\Extension\Core\Type\{TextType, LanguageType, SubmitType, CheckboxType};
use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;
use Symfony\Component\OptionsResolver\OptionsResolver;
use App\Core\Entity\Page;

/**
 * Form for static pages edit
 * ==========================
 *
 * @see Page
 */
class PageType extends AbstractType
{
    /**
     * @see Page
     *
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('title',        TextType::class)
            ->add('language',     LanguageType::class)
            ->add('submitted',    SubmitType::class)
            ->add('is_published', CheckboxType::class)
            ->add('url_name',     TextType::class);

        if ($options['isEditMode'] === true) {
            $this->allowFieldsToBeOptionalInEditMode($builder);
        }
    }

    /**
     * @param OptionsResolver $resolver
     */
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults([
            'data_class' => Page::class,
            'allow_extra_fields' => false,
            'isEditMode' => false,
        ]);
    }

    private function allowFieldsToBeOptionalInEditMode(FormBuilderInterface $builder)
    {
        $builder->addEventListener(FormEvents::PRE_SUBMIT, function (FormEvent $event)  {
            $data = $event->getData();
            $form = $event->getForm();

            foreach ($form->all() as $field) {
                $fieldName = TextUtils::dashesToCamelCase($field->getName());

                if (!isset($data[$fieldName]) || !$data[$fieldName]) {
                    $form->remove($field->getName());
                }
            }
        });
    }
}