Disable backend validation for choice field in Symfony 2 Type

It's confusing but this behaviour is not really validation related as it is caused by the "ChoiceToValueTransformer" which indeed searches for entries in your pre-declared list. If your list is empty or you want to disable the transformer you can simply reset it.

public function buildForm(FormBuilderInterface $builder, array $options){    $builder->add('yourField', 'choice', array('required'=>false));    //more fields...    $builder->get('yourField')->resetViewTransformers();}

Then your custom defined validation will step in (if it exists).

I found the solution

Symfony2.4 form 'This form should not contain extra fields' error

For more details: http://symfony.com/doc/current/cookbook/form/dynamic_form_modification.html#cookbook-dynamic-form-modification-suppressing-form-validation

Add this inside buildForm method in your form type class so that you can validate an input field value rather a choice from a select field value;

$builder->addEventListener(    FormEvents::PRE_SUBMIT,    function (FormEvent $event) {        $form = $event->getForm();        if ($form->has('field')) {            $form->remove('field');            $form->add(                'field',                 'text',                 ['required' => false]            )        }    });