--- /dev/null
+<?php
+
+namespace Drupal\entity_test\Entity;
+use Drupal\Core\Field\BaseFieldDefinition;
+use Drupal\Core\Entity\EntityTypeInterface;
+
+/**
+ * Defines a test entity class with a string ID.
+ *
+ * @ContentEntityType(
+ * id = "entity_test_string_id",
+ * label = @Translation("Test entity with string_id"),
+ * handlers = {
+ * "access" = "Drupal\entity_test\EntityTestAccessControlHandler",
+ * "form" = {
+ * "default" = "Drupal\entity_test\EntityTestForm"
+ * },
+ * "translation" = "Drupal\content_translation\ContentTranslationHandler",
+ * "route_provider" = {
+ * "html" = "Drupal\Core\Entity\Routing\DefaultHtmlRouteProvider",
+ * },
+ * },
+ * base_table = "entity_test_string",
+ * admin_permission = "administer entity_test content",
+ * entity_keys = {
+ * "id" = "id",
+ * "uuid" = "uuid",
+ * "bundle" = "type",
+ * "label" = "name",
+ * },
+ * links = {
+ * "canonical" = "/entity_test_string_id/manage/{entity_test_string_id}",
+ * "add-form" = "/entity_test_string_id/add",
+ * "edit-form" = "/entity_test_string_id/manage/{entity_test_string_id}",
+ * },
+ * field_ui_base_route = "entity.entity_test_string_id.admin_form",
+ * )
+ */
+class EntityTestStringId extends EntityTest {
+
+ /**
+ * {@inheritdoc}
+ */
+ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
+ $fields = parent::baseFieldDefinitions($entity_type);
+ $fields['id'] = BaseFieldDefinition::create('string')
+ ->setLabel(t('ID'))
+ ->setDescription(t('The ID of the test entity.'))
+ ->setReadOnly(TRUE)
+ // In order to work around the InnoDB 191 character limit on utf8mb4
+ // primary keys, we set the character set for the field to ASCII.
+ ->setSetting('is_ascii', TRUE);
+ return $fields;
+ }
+
+}