BookOutlineConstraintValidator.php

<?php

namespace Drupal\book\Plugin\Validation\Constraint;

use Drupal\book\BookManagerInterface;
use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

/**
 * Constraint validator for changing the book outline in pending revisions.
 */
class BookOutlineConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
    
    /**
     * The book manager.
     *
     * @var \Drupal\book\BookManagerInterface
     */
    protected $bookManager;
    
    /**
     * Creates a new BookOutlineConstraintValidator instance.
     *
     * @param \Drupal\book\BookManagerInterface $book_manager
     *   The book manager.
     */
    public function __construct(BookManagerInterface $book_manager) {
        $this->bookManager = $book_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('book.manager'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function validate($entity, Constraint $constraint) {
        if (isset($entity) && !$entity->isNew() && !$entity->isDefaultRevision()) {
            
            /** @var \Drupal\Core\Entity\ContentEntityInterface $original */
            $original = $this->bookManager
                ->loadBookLink($entity->id(), FALSE) ?: [
                'bid' => 0,
                'weight' => 0,
            ];
            if (empty($original['pid'])) {
                $original['pid'] = -1;
            }
            if ($entity->book['bid'] != $original['bid']) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->atPath('book.bid')
                    ->setInvalidValue($entity)
                    ->addViolation();
            }
            if ($entity->book['pid'] != $original['pid']) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->atPath('book.pid')
                    ->setInvalidValue($entity)
                    ->addViolation();
            }
            if ($entity->book['weight'] != $original['weight']) {
                $this->context
                    ->buildViolation($constraint->message)
                    ->atPath('book.weight')
                    ->setInvalidValue($entity)
                    ->addViolation();
            }
        }
    }

}