SQLAlchemy keyset && offset/limit pagination query mixin

sqla_pagination.py

class PaginationMixin(object):

    def paginate(self, order_by=None, order_dir=None, limit=None, cursor=None, page=None):
        assert not page or not cursor, 'should not combine cusor and page'

        # convert arguments
        if isinstance(order_by, str):
            order_by = getattr(self._primary_entity.expr._identity_class, order_by)

        # check arguments
        if (order_by is not None) and (not isinstance(order_by, InstrumentedAttribute)):
            raise ValueError('Unrecognized type for order_by: %s' % type(order_by))

        if order_dir not in {'asc', 'desc', None}:
            raise ValueError('Unrecognized value for order_dir: %s' % order_dir)

        if (limit is not None) and (limit <= 0):
            raise ValueError('Unrecognized value for limit: %s' % order_dir)

        query = self

        if cursor is not None:
            if order_dir == 'desc':
                query = query.filter(order_by < cursor)
            else:
                query = query.filter(order_by > cursor)

        if order_by is not None:
            if order_dir == 'desc':
                query = query.order_by(order_by.desc())
            else:
                query = query.order_by(order_by)

        if page:
            query = query.offset(limit * (page - 1))

        if limit is not None:
            query = query.limit(limit)

        return query

    def paginate_all(self, order_by='id', order_dir='asc', limit=10, cursor=None):
        while True:
            objects = self.paginate(order_by=order_by, order_dir=order_dir, limit=limit, cursor=cursor).all()
            if objects:
                yield objects, {'cursor': cursor}
                cursor = getattr(objects[-1], order_by)
            else:
                break