public function configureCrud(Crud $crud): Crud
{
    $crud->setFormOptions([
        'attr' => [
            'data-controller' => 'coupon' // = <form data-controller="coupon" ...>
        ]
    ]);
 }
 
public function configureFields(string $pageName): iterable
{
  yield TextField::new('code', 'Code')
      ->setFormTypeOptions([
          'attr' => [
              'data-coupon-target' => 'input'
          ]
      ])
      ->setHelp('<a data-action="coupon#generate" class="btn btn-primary" href="#">Generate random code</a>')
  ;
}