/**
  * Attempts to resolve the fetch mode.
  *
  * @param string $className The class name
  * @param string $fetchMode The fetch mode
  * @return integer The fetch mode as defined in ClassMetadata
  * @throws MappingException If the fetch mode is not valid
  */
 private function getFetchMode($className, $fetchMode)
 {
     if (!defined('Doctrine\\ORM\\Mapping\\ClassMetadata::FETCH_' . $fetchMode)) {
         throw MappingException::invalidFetchMode($className, $fetchMode);
     }
     return constant('Doctrine\\ORM\\Mapping\\ClassMetadata::FETCH_' . $fetchMode);
 }