Do not rely on notifiction module being imported
This has worked so far mostly by accident, but it turned out to be
brittle while writing tests. This makes sure that the notification
module is always imported before use.
"""
Field-like classes that aren't really fields. It's easier to use objects that
have the same attributes as fields sometimes (avoids a lot of special casing).
"""
from django.db.models import fields
class OrderWrt(fields.IntegerField):
"""
A proxy for the _order database field that is used when
Meta.order_with_respect_to is specified.
"""
name = '_order'
attname = '_order'
column = '_order'