Issue #3292166 by kristiaanvandeneynde: Add a way to wrap config entities

    $group_content_type->save(TRUE);

  }

}

/**

 * Introduce the group_config_wrapper entity type.

 */

function group_update_9208() {

  $definition_update_manager = \Drupal::entityDefinitionUpdateManager();

  if (!$definition_update_manager->getEntityType('group_config_wrapper')) {

    $entity_type = \Drupal::entityTypeManager()->getDefinition('group_config_wrapper');

    $definition_update_manager->installEntityType($entity_type);

  }

}

<?php

namespace Drupal\group\Entity\Access;

use Drupal\Core\Access\AccessResult;

use Drupal\Core\Cache\Cache;

use Drupal\Core\Entity\EntityAccessControlHandler;

use Drupal\Core\Entity\EntityHandlerInterface;

use Drupal\Core\Entity\EntityInterface;

use Drupal\Core\Entity\EntityTypeInterface;

use Drupal\Core\Session\AccountInterface;

use Symfony\Component\DependencyInjection\ContainerInterface;

/**

 * Access controller for the ConfigWrapper entity.

 *

 * @see \Drupal\group\Entity\ConfigWrapper.

 */

class ConfigWrapperAccessControlHandler extends EntityAccessControlHandler implements EntityHandlerInterface {

  /**

   * {@inheritdoc}

   */

  public static function createInstance(ContainerInterface $container, EntityTypeInterface $entity_type) {

    return new static($entity_type);

  }

  /**

   * {@inheritdoc}

   */

  protected function checkAccess(EntityInterface $entity, $operation, AccountInterface $account) {

    return AccessResult::forbidden('Config wrappers should only exist in code.')->setCacheMaxAge(Cache::PERMANENT);

  }

  /**

   * {@inheritdoc}

   */

  protected function checkCreateAccess(AccountInterface $account, array $context, $entity_bundle = NULL) {

    return AccessResult::forbidden('Config wrappers should only exist in code.')->setCacheMaxAge(Cache::PERMANENT);

  }

}

<?php

namespace Drupal\group\Entity;

use Drupal\Core\Entity\ContentEntityBase;

use Drupal\Core\Entity\EntityTypeInterface;

use Drupal\Core\Field\BaseFieldDefinition;

/**

 * Defines the ConfigWrapper entity.

 *

 * @ingroup group

 *

 * @ContentEntityType(

 *   id = "group_config_wrapper",

 *   label = @Translation("Config wrapper"),

 *   label_singular = @Translation("config wrapper"),

 *   label_plural = @Translation("config wrappers"),

 *   label_count = @PluralTranslation(

 *     singular = "@count config wrapper",

 *     plural = "@count config wrappers"

 *   ),

 *   handlers = {

 *     "access" = "Drupal\group\Entity\Access\ConfigWrapperAccessControlHandler",

 *     "storage_schema" = "Drupal\group\Entity\Storage\ConfigWrapperStorageSchema",

 *   },

 *   base_table = "group_config_wrapper",

 *   entity_keys = {

 *     "id" = "id",

 *     "bundle" = "bundle",

 *   },

 * )

 */

class ConfigWrapper extends ContentEntityBase implements ConfigWrapperInterface {

  /**

   * {@inheritdoc}

   */

  public function getConfigEntity() {

    return $this->get('entity_id')->entity;

  }

  /**

   * {@inheritdoc}

   */

  public function getConfigEntityId() {

    return $this->get('entity_id')->target_id;

  }

  /**

   * {@inheritdoc}

   */

  public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {

    $fields = parent::baseFieldDefinitions($entity_type);

    $fields['entity_id'] = BaseFieldDefinition::create('entity_reference')

      ->setLabel(t('Config'))

      ->setDescription(t('The config entity to wrap.'))

      // Required to force a string data type.

      ->setSetting('target_type', 'group_type')

      ->setRequired(TRUE)

      ->setReadOnly(TRUE);

    return $fields;

  }

  /**

   * {@inheritdoc}

   */

  public static function bundleFieldDefinitions(EntityTypeInterface $entity_type, $bundle, array $base_field_definitions) {

    $fields['entity_id'] = clone $base_field_definitions['entity_id'];

    $fields['entity_id']->setSetting('target_type', $bundle);

    return $fields;

  }

}

<?php

namespace Drupal\group\Entity;

use Drupal\Core\Entity\ContentEntityInterface;

/**

 * Provides an interface defining a ConfigWrapper entity.

 *

 * @ingroup group

 */

interface ConfigWrapperInterface extends ContentEntityInterface {

  /**

   * Returns the wrapped config entity.

   *

   * @return \Drupal\Core\Config\Entity\ConfigEntityInterface

   *   The wrapped config entity.

   */

  public function getConfigEntity();

  /**

   * Returns the wrapped config entity ID.

   *

   * @return string

   *   The wrapped config entity ID.

   */

  public function getConfigEntityId();

}

<?php

namespace Drupal\group\Entity\Storage;

use Drupal\Core\Entity\ContentEntityTypeInterface;

use Drupal\Core\Entity\Sql\SqlContentEntityStorageSchema;

use Drupal\Core\Field\FieldStorageDefinitionInterface;

/**

 * Defines the config wrapper schema handler.

 */

class ConfigWrapperStorageSchema extends SqlContentEntityStorageSchema {

  /**

   * {@inheritdoc}

   */

  protected function getEntitySchema(ContentEntityTypeInterface $entity_type, $reset = FALSE) {

    $schema = parent::getEntitySchema($entity_type, $reset);

    if ($base_table = $this->storage->getBaseTable()) {

      $schema[$base_table]['indexes'] += [

        $this->getEntityIndexName($entity_type, 'load_by_config') => ['bundle', 'entity_id'],

      ];

    }

    return $schema;

  }

  /**

   * {@inheritdoc}

   */

  protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $storage_definition, $table_name, array $column_mapping) {

    $schema = parent::getSharedTableFieldSchema($storage_definition, $table_name, $column_mapping);

    $field_name = $storage_definition->getName();

    if ($field_name === 'entity_id') {

      $schema['fields'][$field_name]['not null'] = TRUE;

    }

    return $schema;

  }

}