Modify label_attr field in Symfony 5 form builder - forms

Question

When building a form in symfony form builder changing the choice attribute can be done.
However, for the label attribute this doesn't seem possible.
Here is how i modify the choice:
$builder->add('type', EntityType::class, [
'class' => Resourcetype::class,
'multiple' => true,
'expanded' => true,
'choice_attr' => function (?Resourcetype $type) {
return ['class' => $type->getSafeName() . '-parent parent' : $type->getSafeName()
];
});
Is this possible for the label_attr field?

Answer 1

EntityType doesn't provide option for modifying choice label attributes.
You should do it yourself.
1. Simple solution
Iterate over choices in templating engine, one by one and render it yourselves. Obtain entity from choice and set label attribute.
{{ form_start(form) }}
{%- for choice in form.choices %}
<div>
{% set entity = form.choices.vars.choices[choice.vars.value].data %}
{{ form_widget(choice) }}
{{ form_label(choice, null, {
label_attr: {class: 'test-' ~ entity.number}
}) }}
</div>
{% endfor -%}
{{ form_end(form) }}
2. Clean solution
Create custom type extending EntityType:
https://symfony.com/doc/current/form/create_custom_field_type.html
Create new option in type definition allowing closures e.g. "choice_label_attr" and pass closure to view:
// src/Form/Type/CustomEntityType.php
namespace App\Form\Type;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Bridge\Doctrine\Form\Type\EntityType;
class CustomEntityType extends AbstractType
{
public function configureOptions(OptionsResolver $resolver): void
{
$resolver->setRequired('choice_label_attr');
}
public function buildView(FormView $view, FormInterface $form, array $options)
{
$view->vars['choice_label_attr'] = $options['choice_label_attr']
}
public function getParent(): string
{
return EntityType::class;
}
}
Extend template for choice type:
https://symfony.com/doc/current/form/form_themes.html#applying-themes-to-all-forms
Use "choice_label_attr" callback inside extended template:
{% use "bootstrap_4_layout.html.twig" %}
{% block custom_entity_widget_expanded -%}
<div {{ block('widget_container_attributes') }}>
{%- for child in form %}
{{- form_widget(child) -}}
{{- form_label(child, null, {class: choice_label_attr(form.choices.vars.choices[child.vars.value].data), translation_domain: choice_translation_domain}) -}}
{% endfor -%}
</div>
{%- endblock custom_entity_widget_expanded %}
More info: https://github.com/symfony/symfony/blob/5.x/src/Symfony/Bridge/Twig/Resources/views/Form/bootstrap_4_layout.html.twig
Usage example:
use App\Form\Type\CustomEntityType ;
$builder->add('type', CustomEntityType::class, [
'class' => Resourcetype::class,
'multiple' => true,
'expanded' => true,
'choice_attr' => function (?Resourcetype $type) {
return [
'class' => sprintf('%s-parent parent', $type->getSafeName()) : $type->getSafeName()
];
});
Solution 2. is written from head and can contain some bugs but I hope you get the idea.
Both solution are using Twig and Bootstrap 4 form layout, but it is not requirement.