utils.py

import zlib


# TODO(davedash): liberate this
def manual_order(qs, pks, pk_name='id'):
    """
    Given a query set and a list of primary keys, return a set of objects from
    the query set in that exact order.
    """

    if not pks:
        return qs.none()

    objects = qs.filter(id__in=pks).extra(
            select={'_manual': 'FIELD(%s, %s)'
                % (pk_name, ','.join(map(str, pks)))},
            order_by=['_manual'])

    return objects


crc32 = lambda x: zlib.crc32(x) & 0xffffffff