vlan.py 文件源码

def filter_active_router_addresses(gwportprefixes):
    """Filters a GwPortPrefix queryset, leaving only active router addresses.

    For any given prefix, if multiple router addresses exist, the lowest IP
    address will be picked.  If the prefix has a virtual address, it will be
    picked instead.

    :param gwportprefixes: A GwPortPrefix QuerySet.
    :returns: A list of GwPortPrefix objects.

    """
    # It is more or less impossible to get Django's ORM to generate the
    # wonderfully complex SQL needed for this, so we do it by hand.
    raddrs = gwportprefixes.order_by('prefix__id', '-virtual', 'gw_ip')
    grouper = groupby(raddrs, attrgetter('prefix_id'))
    return [next(group) for _key, group in grouper]