Allow to add a new value in a choice Field Type

Question

I use Form Component and have a choice Field Type on a form which is rendered to a select field. On a client-side I use select2 plugin which initializes the select with the sett

Answer 1

The problem is in a choice transformer, which erases values that don't exist in a choice list.
The workaround with disabling the transformer helped me:

public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder->add('choiceField', 'choice', ['choices' => $someList]);

    // more fields...

    $builder->get('choiceField')->resetViewTransformers();
}