PHP Symfony FormType EntityCollection into Choices

I am beginner in PHP and Symfony and I started recently on a project.

We have 2 entities which are related by doctrine Annotation ManyToMany with JoinTable

Example: entity and datatable Room, entity and datatable Person and datatable RoomPerson (entity does not exist and just exist in doctrine annotation JoinTable).

The entity Room has a property Collection of Persons.

With a formType it is rendered in page as a select html element multiple (so we can choose several persons)

FormType with preEvent to fill list of possible persons:

$allowedPersons = $this->em->getRepository(Person::class)->findBy(***);
    $form
        ->add('personList', EntityType::class, [
            'class' => Person::class,
            'choices' => $allowedPersons ,

public function configureOptions(OptionsResolver $resolver)
{
    $resolver->setDefaults([
        'data_class' => Room::class,

New request is to order the list of Persons.

So I made changes described in some tutorials to change declare the Entity RoomPerson et remove annotations ManyToMany for ManyToOne and OneToMany. I added the property "Order" on RoomPerson. I Added the methods AddRoomPerson and RemoveRoomPerson to make updates of the list by the mapping of my FormType.

So my entity "Room" now only contains a property Collection of RoomPerson. But I don't know how to use it in my FormType because I always want to show the list of Persons.

I tried a lot of things without success.

example:

$allowedPersons = $this->em->getRepository(Person::class)->findBy(***);
    $form
        ->add('roomPersonList', EntityType::class, [
            'class' => RoomPerson::class,
            'choices' => $allowedPersons ,
            'choice_value' => function(?RoomPerson $roomPerson) {
                return $roomPerson? $roomPerson->getPerson()->getIdPerson() : '';
            },
            'choice_label' => function(?RoomPerson $roomPerson) {
                return $roomPerson? $roomPerson->getPerson()->getName() : '';
            },

I get following error:

Argument 1 passed to App\Form\RoomPersonType::App\Form{closure}() must be an instance of App\Entity\RoomPerson or null, instance of App\Entity\Person given, called in ..\vendor\symfony\form\ChoiceList\ArrayChoiceList.php on line 200"

So please I need help to transform my list of RoomPerson in my formtype and to make an update of this list in page.

source https://stackoverflow.com/questions/70114021/php-symfony-formtype-entitycollection-into-choices