--- /dev/null
+<?php
+
+namespace Drupal\path\Plugin\Validation\Constraint;
+
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+/**
+ * Constraint validator for changing path aliases in pending revisions.
+ */
+class PathAliasConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
+
+ /**
+ * The entity type manager.
+ *
+ * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+ */
+ private $entityTypeManager;
+
+ /**
+ * Creates a new PathAliasConstraintValidator instance.
+ *
+ * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+ * The entity type manager.
+ */
+ public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+ $this->entityTypeManager = $entity_type_manager;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function create(ContainerInterface $container) {
+ return new static(
+ $container->get('entity_type.manager')
+ );
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function validate($value, Constraint $constraint) {
+ $entity = !empty($value->getParent()) ? $value->getEntity() : NULL;
+
+ if ($entity && !$entity->isNew() && !$entity->isDefaultRevision()) {
+ /** @var \Drupal\Core\Entity\ContentEntityInterface $original */
+ $original = $this->entityTypeManager->getStorage($entity->getEntityTypeId())->loadUnchanged($entity->id());
+ if ($value->alias != $original->path->alias) {
+ $this->context->addViolation($constraint->message);
+ }
+ }
+ }
+
+}