Symfony 5.1 Dynamic Generation for Submitted Forms - No display - symfony

Question

I'm embarking on this new post because despite a lot of research I'm stuck.
I have three entities.
Employee -> ManyToOne -> RefSociety
Employee -> ManyToOne -> RefSite
RefSociety -> OnToMany -> RefSite
RefSociety -> OnToMany -> Employee
RefSite -> OnToMany -> Employee
RefSite -> ManyToOne -> RefSociety
I am using the symfony documentation from FormEvent ; https://symfony.com/doc/current/form/dynamic_form_modification.html#dynamic-generation-for-submitted-forms
I want that in my Employee form, when I select a society, then, it only offers me the sites attached to this society.
Here is what I have already done. I have tried a lot of different ways. When I manually pass a SocietyId, then it recognizes it and shows me the desired sites.
Also I don't think it's the JavaScript side that is blocking. Do you have an idea ?
EmployeeType.php
class EmployeeType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('societe', EntityType::class, [
'class' => RefSociety::class,
'placeholder' => 'Sélectionnez votre société',
'mapped' => false,
])
;
$formModifier = function (FormInterface $form, ?RefSociety $society)
{
$sites = null === $society ? [] : $society->getSites();
$form->add('site', EntityType::class, [
'class' => RefSite::class,
'placeholder' => 'Sélectionnez votre site',
'choices' => $sites,
]);
};
$builder->addEventListener(
FormEvents::PRE_SET_DATA,
function (FormEvent $event) use ($formModifier)
{
$data = $event->getData();
$formModifier($event->getForm(), $data->getSociete());
}
);
$builder->get('societe')->addEventListener(
FormEvents::POST_SUBMIT,
function (FormEvent $event) use ($formModifier)
{
$society = $event->getForm()->getData();
$formModifier($event->getForm()->getParent(), $society);
}
);
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults([
'data_class' => Employee::class,
]);
}
}
index.html.twig
{{ form_start(employeeForm) }}
{{form_row(employeeForm.societe) }}
{{form_row(employeeForm.site) }}
{{ form_end(employeeForm) }}
<script>
var $society = $('#employee_societe');
$society.change(function () {
var $employeeForm = $(this).closest('employeeForm');
var data = {};
data[$society.attr('name')] = $society.val();
//console.log(data)
$.ajax({
url: $employeeForm.attr('action'),
type: $employeeForm.attr('method'),
data: data,
success: function (html) {
//console.log(data)
$('#employee_site').replaceWith(
$(html).find('#employee_site')
);
}
});
});
</script>