@classmethod
def get_dbmodel_attribute_name(cls, attr_name):
    """
        Given the name of an attribute of the entity class give the corresponding name of the attribute
        in the db model.  It if doesn't exit this raises a ValueError

        :param attr_name:
        :return: the dbmodel attribute name
        :rtype: str
        """
    if hasattr(cls.MODEL_CLASS, attr_name):
        return attr_name
    raise ValueError("Unknown attribute '{}'".format(attr_name))
