drupal-graphql / graphql

 *   deriver = "Drupal\graphql_core\Plugin\Deriver\Fields\ConfigEntityPropertyDeriver",

 * )

 */

class ConfigEntityProperty extends EntityFieldBase {

  /**

   * {@inheritdoc}

   */

  public function resolveValues($value, array $args, ResolveInfo $info) {

    $definition = $this->getPluginDefinition();

    $property = $definition['property'];

    $result = $value->get($property);

    if (($type = $info->getReturnType()->getNamedType()) && $type instanceof AbstractScalarType) {

      $result = $type->serialize($result);

    }

    yield $result;

  }

}

/**

 * Base class for entity field plugins.

 */

class EntityFieldBase extends FieldPluginBase {

  /**

   * {@inheritdoc}

   */

  protected function resolveItem($item, array $args, ResolveInfo $info) {

    if ($item instanceof FieldItemInterface) {

      $definition = $this->getPluginDefinition();

      $property = $definition['property'];

      $result = $item->get($property)->getValue();

      if (($type = $info->getReturnType()->getNamedType()) && $type instanceof AbstractScalarType) {

        $result = $type->serialize($result);

      }

      return $result;

    }

  }

}