Symfony Form - Custom collection entry theme block for block_prefix

Question

I have a custom CollectionType-Form-Class and I want to write some stuff in the theme for the entries of this type.

The problem is that this is somewhat of a "general FormType" in this project, so others will use this CollectionType, too. I don't know their forms and stuff, so I can't make use of the automatically generated block names like _my_form_my_collection_entry_widget and so on.

I have to create a reusable CollectionType with add- / remove-buttons, so that my colleagues don't always have to manually add those buttons and the necessary JS. I wanted to add the remove-button after every entry. Of course I tried the widget-block of my CollectionType, loop through the children, render the rows of those children and add my remove-button, but unfortunately, with this approach, the prototype-data-attribute got lost.

I've set the "block_prefix" for the CollectionType and I can use block_prefix_widget and block_prefix_row, but what I really need is block_prefix_entry_widget.

I can use collection_entry_widget, this would be the correct block, but it affects all collections, not just my custom one.

My code roughly looks like this:

class ProjectFormType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $builder->add('project_date_span_collection', ExpandableCollectionType::class, [
            'entry_type' => DateSpanType::class,
            'allow_add' => true,
            'allow_delete' => true,
            'prototype' => true,
        ]);
    }
}


class ExpandableCollectionType extends AbstractType
{
    public const BLOCK_PREFIX = 'expandable_collection';

    public function getBlockPrefix(): string
    {
        return self::BLOCK_PREFIX;
    }

    public function getParent(): string
    {
        return CollectionType::class;
    }
}

class DateSpanType extends AbstractType
{
    public const BLOCK_PREFIX = 'date_span';

    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $builder
            ->add('from', DateType::class, [
                'label' => 'From',
                'label_attr' => ['class' => 'label-date-span-from'],
                'widget' => 'choice',
                'format' => 'dd.MM.yyyy',
                'html5' => false,
            ])
            ->add('to', DateType::class, [
                'label' => 'To',
                'label_attr' => ['class' => 'label-date-span-to'],
                'widget' => 'choice',
                'format' => 'dd.MM.yyyy',
                'html5' => false,
            ]);
    }

    public function getBlockPrefix(): string
    {
        return self::BLOCK_PREFIX;
    }
}

// example controller code:

// .....
$form = $this->createFormBuilder(ProjectFormType::class)
    ->getForm();
// .....
return $this->render('/form.html.twig', array('form' => $form->createView()));

I know I might have stuff like _project_form_project_date_span_collection_entry_widget or stuff like that but that won't suffice, because this CollectionType will be used in many different forms with different names and also with different entry types. I would need something like expandable_collection_entry_widget to cover all the different occurences.

I tried many different combinations of block names, many didn't work, the working ones weren't what I needed.

I also added var_dump($blockName) in vendor/symfony/twig-bridge/Form/TwigRendererEngine.php, but all I've seen where those automatically generated block names that won't do the trick for my needs.