def with_fields(self, *fields):
        """Returns list of characters with information for certain fields.

        Parameters
        ----------
        *fields : list of str
            fields for which information should be available

        Returns
        -------
        :class:`sqlalchemy.orm.query.Query` :
            list of matches
        """
        Unihan = self.sql.base.classes.Unihan
        query = self.sql.session.query(Unihan)
        for field in fields:
            query = query.filter(Column(field).isnot(None))
        return query