Convert communication namedtuple to this class.

        Args:
            pub (obj): :class:`.Publication` instance which will be converted.

        Returns:
            obj: :class:`DBPublication` instance.

def from_comm(cls, pub):
        '''
        Convert communication namedtuple to this class.

        Args:
            pub (obj): :class:`.Publication` instance which will be converted.

        Returns:
            obj: :class:`DBPublication` instance.
        '''
        filename = None
        if pub.b64_data:
            filename = cls._save_to_unique_filename(pub)

        return cls(
            title=pub.title,
            author=pub.author,
            pub_year=pub.pub_year,
            isbn=pub.isbn,
            urnnbn=pub.urnnbn,
            uuid=pub.uuid,
            aleph_id=pub.aleph_id,
            producent_id=pub.producent_id,
            is_public=pub.is_public,
            filename=pub.filename,
            is_periodical=pub.is_periodical,
            path=pub.path,

            file_pointer=filename
        )