tos/EventListener/RegistrationListener.php

<?php
namespace vierbergenlars\AuthserverTosBundle\EventListener;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Registration\RegistrationEvents;
use Registration\Event\RegistrationFormEvent;
use Registration\Event\RegistrationHandleEvent;
use Symfony\Component\Form\Extension\Core\Type\CheckboxType;
use Symfony\Component\Validator\Constraints\IsTrue;
use vierbergenlars\AuthserverTosBundle\Entity\UserTos;
use Doctrine\ORM\EntityManagerInterface;

class RegistrationListener implements EventSubscriberInterface
{

    private $tosUrl;

    private $tosVersion;

    /**
     *
     * @var EntityManagerInterface
     */
    private $em;

    public static function getSubscribedEvents()
    {
        return [
            RegistrationEvents::BUILD_FORM => [
                'onBuildForm',
                -200
            ],
            RegistrationEvents::HANDLE_FORM => [
                'onHandleForm',
                -20 // After persisting user
            ]
        ];
    }

    public function __construct($tosUrl, $tosVersion, EntityManagerInterface $em)
    {
        $this->tosUrl = $tosUrl;
        $this->tosVersion = $tosVersion;
        $this->em = $em;
    }

    public function onBuildForm(RegistrationFormEvent $event)
    {
        $event->getFormBuilder()->add('vl_tos_accept', CheckboxType::class, [
            'label' => 'I accept the <a href="' . htmlentities($this->tosUrl, ENT_HTML5 | ENT_QUOTES) . '">terms of service</a>',
            'mapped' => false,
            'attr' => [
                'align_with_widget' => true
            ],
            'constraints' => [
                new IsTrue([
                    'message' => 'You must accept the terms of service.'
                ])
            ]
        ]);
    }

    public function onHandleForm(RegistrationHandleEvent $event)
    {
        if ($event->getForm()
            ->get('vl_tos_accept')
            ->getData()) {
            $user = $event->getForm()->getData();
            /* @var $user \App\Entity\User */
            $tosUser = new UserTos($user);
            $tosUser->setAcceptedVersion($this->tosVersion);
            $this->em->persist($tosUser);
        }
    }
}