Django proxy model and ForeignKey

Question

How to make entry.category to be instance of CategoryProxy? See code for details:

class Category(models.Model): pass

class Entry(models.Model):
    category = models.ForeignKey(Category)

class EntryProxy(Entry):
    class Meta:
        proxy = True

class CategoryProxy(Category):
    class Meta:
        proxy = True

entry = EntryProxy.objects.get(pk=1)
entry.category # !!! I want CategoryProxy instance here

Cast from Category to CategoryProxy is ok too, but I am not very familiar with ORM internals to properly copy internal state...

EDIT. Reason: I added method to CategoryProxy and want to use him:

EntryProxy.objects.get(pk=1).category.method_at_category_proxy()

EDIT 2. Currently I implemented it like this:

EntryProxy._meta.get_field_by_name('category')[0].rel.to = CategoryProxy

but it looks terrible...

Answer 1

Define a property category on EntryProxy that looks up the CategoryProxy by its id:

class EntryProxy(Entry):
    @property
    def category(self):
        cid = super(EntryProxy, self).category.id
        return CategoryProxy.objects.get(id=cid)

    class Meta:
        proxy = True

Answer 2

Joseph Spiros's answer to one of my questions might help you:

http://stackoverflow.com/questions/3176731/django-inheritance-and-permalinks/3183803#3183803

I'm not sure how it'll work with proxy models.