Custom Django manager that excludes subclasses
When you're using Django model inheritance, sometimes you want to be able to get objects of the base class that aren't instances of any of the subclasses. You might expect the obvious way of doing this, `SuperModel.objects.filter(submodel__isnull=True)`, to work, but unfortunately it doesn't. (Neither does `SuperModel.objects.filter(submodel__supermodel_ptr=None)`, or any other convoluted way I could think of doing it.) Here's a nicer approach for doing this. [The blog entry is here.](http://sciyoshi.com/blog/2008/aug/07/custom-django-manager-excludes-subclasses/)
- managers
- models
- model
- subclass
- manager
- inheritance
- subclasses