Use different validation groups depending on which submit button is clicked

FoobarType.php

<?php

namespace Acme\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\OptionsResolver\OptionsResolverInterface;

class FoobarType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder
            ->add('foobar', 'text')
            ->add('barfoo', 'text')
            ->add('refresh', 'submit')
            ->add('save', 'submit');
    }

    public function setDefaultOptions(OptionsResolverInterface $resolver)
    {
        $resolver->setDefaults(array(
            'validation_groups' => function(FormInterface $form) {
                // If refresh button is clicked, use "Refresh" validation group
                if ($form->get('refresh')->isClicked()) {
                    return array('Refresh');
                }

                // Else use "Default" validation group
                return array('Default');
            }
        ));
    }

    public function getName()
    {
        return 'foobar';
    }
}