@classmethod
def get_natural_key_info(cls):
    """
        Derive natural key from first unique_together definition, noting
        which fields are related objects vs. regular fields.
        """
    fields = cls.get_natural_key_definition()
    info = []
    for name in fields:
        field = cls._meta.get_field(name)
        rel_to = None
        if hasattr(field, 'rel'):
            rel_to = field.rel.to if field.rel else None
        elif hasattr(field, 'remote_field'):
            if field.remote_field:
                rel_to = field.remote_field.model
            else:
                rel_to = None
        info.append((name, rel_to))
    return info
