Django Manager for Group模型不起作用-返回空的查询集

Question

I'm junior dev. I want to create managers for Django Groups. One new one and one that will override default manager EDIT: Django 1.8, python 2.7.15

My managers:

class DefaultGroupManager(models.Manager):
    def get_queryset(self):
        test_ids = Test.objects.values_list('rel_group_id', flat=True)
        return super(DefaultGroupManager, self).get_queryset().exclude(id__in=test_ids)


class AllGroupsManager(models.Manager):
    def get_queryset(self):
        return super(AllGroupsManager, self).get_queryset().exclude(rel_group__start_date__lte=datetime.now()-timedelta(days=30))

With these managers I created something like this:

dgm = DefaultGroupManager()
agm = AllGroupsManager()
agm.contribute_to_class(Group, 'get_all')
dgm.contribute_to_class(Group, 'objects')

And it was working. I could use Group.get_all.all() and new Group.objects.all() . In return I had proper lists of objects.

But my senior dev said that I have to do it by creating the new Group model that inherits from Group. So I did:

My Group model:

class GroupModel(Group):
    get_all = DefaultGroupManager()
    objects = AllGroupsManager()

But it does not work!

When I use GroupModel.get_all.all() or overrided GroupModel.objects.all() it returns empty list [] instead of list with loads of objects.

Everything seems to be good :(

I will appreciate any help!

Answer 1

If you're defining a new class, you definitely want to make it a proxy for Group. Otherwise it will have its own database table, which as you've found won't have any data in it.

class GroupModel(Group):
    get_all = DefaultGroupManager()
    objects = AllGroupsManager()

    class Meta:
        proxy = True