Symfony4 - 表单choice_value中的空值不起作用

Question

When I'm using a choice_value function in order to exclude some data in my select, if the field is empty, a value is set to database but not "NULL". this value is the first entry of my entity. When I list all data, if the field is empty, "Null" value is set in database.

Any ideas ?

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $this->currentId = $options['currentId'];
     $builder

         ->add('oldOwners', entityType::class, array(
             'class' => OldOwners::class,
             'required' => false,
             'empty_data' => null,
             'multiple' => false,
             'choice_value' => function (OldOwners $oldOwners = null) {
                 if ($oldOwners != null && $oldOwners != '') {
                     if ($this->currentId != 0 && $oldOwners->animal->getId() == $this->currentId)

                         return $oldOwners->getDateDisposal()->format('Y-m-d');
                 }

             },
             'choice_label' => function (OldOwners $oldOwners = null) {

                 if ($oldOwners != null && $oldOwners != '') {
                     if ($this->currentId != 0 && $oldOwners->animal->getId() == $this->currentId)

                         return $oldOwners->getDateDisposal()->format('Y-m-d');
                 }
             },

             'label' => "Date"));

 /**
 * @param OptionsResolver $resolver
 */
public function configureOptions(OptionsResolver $resolver)
{
    $resolver->setDefaults([
        'data_class' => Adopting::class,
        'currentId' => null,
    ]);
    $resolver->setRequired('currentId');
}

Answer 1

When I list all data, if the field is empty, "Null" value is set in database.

For this part it's because your 'empty_data' => null

take a look at doc