Description

In some cases in EntityType we need to use Select2 for speedup rendering tens of thousend rows in field

If I use 'choices' => [] we will got validate errors from selected with Select2 field

Would be greate to have 'ajax' => true option, which dont send on frontend choices, but validate submitted data, as traditional

WDYT?

Example

 $builder
            ->add('contact', EntityType::class, [
                'class' => Contact::class,
                'choice_label' => 'name',
                'required' => true,
                'placeholder' => '',
                'ajax' => true,
            ])