Avoid validation errors when selecting a dependent field first, then modifying the field it relies on

[gremo]

I've a simple form with two fields:

• Office (headquarter)
• User (employee) selection that depends on office selection

I want to be able to select "any user" (that doesn't belong to any office)... or select the office and see the list of users.

public function buildForm(FormBuilderInterface $builder, array $options): void
{
    $builder = new DynamicFormBuilder($builder);
    $builder
        ->add('office', ChoiceType::class, [
            'placeholder' => 'Qualsiasi sede',
            'choices' => $this->handle(new FetchCompanyOfficesMessage($options['profile'])),
            'choice_value' => fn(?CompanyOffice $c) => $c->id ?? '',
            'choice_label' => fn(?CompanyOffice $c) => $c?->name ?? '',
        ])
        ->addDependent('user', 'office', function (DependentField $field, ?CompanyOffice $office) use ($options) {
            $field->add(ChoiceType::class, [
                'choices' => $this->handle(new FetchRemoteUsersMessage($options['profile'], $office)),
                'placeholder' => 'Qualsiasi dipendente',
                'choice_value' => fn(?User $u) => $u?->id ?? '',
                'choice_label' => fn(?User $u) => $u?->fullName ?? '',
            ]);
        })
    ;
}

When you select an office, the form dynamically updates to display only the employees associated with that office. So far so good.

The issue occurs when you first select a user, then choose an office the user doesn't belong to:

After selecting an office, the users list updates, and the previously selected user disappears (id: 35). However, the data sent to the server (as well as the live property value) still holds the old, now invalid, user. As a result, the form isn't submitted due to a validation error:

Is there any option to avoid this behaviour?

[gremo]

Closing if favour of symfony/ux#2240