Generic Foreign Keys WTF?!

Generic Foreign Keys WTF?!

In models.py
--------------------
from datetime import datetime
from django.db import models
from django.contrib.sites.models import Site
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic


class Cart(models.Model):
    """
    Container to hold all the orders that a user of the website makes including
    trips, addons, extras, etc.
    """
    date_added = models.DateTimeField(auto_now_add=True)
    date_updated = models.DateTimeField(auto_now=True)
    site = models.ForeignKey(Site, default=Site.objects.get_current)
    order_items = generic.GenericRelation('GenericItem')
   
    class Meta:
        abstract = True
        
        
class ShoppingCart(Cart):
    name = models.CharField(max_length=50)
    

class Item(models.Model):
    date_added = models.DateTimeField(auto_now_add=True, default=datetime.now())
    date_updated = models.DateTimeField(auto_now=True, default=datetime.now())
    
    class Meta:
        abstract = True
        
        
class GenericItem(Item):
    content_type = models.ForeignKey(ContentType)
    object_id = models.IntegerField()
    content_object = generic.GenericForeignKey('content_type', 'object_id')
    
    
class BookItem(GenericItem):
    title = models.CharField(max_length=50)
    num_pages = models.IntegerField()
    
    def __unicode__(self):
        return "Book: %s" % self.title
    
    
class MovieItem(GenericItem):
    title = models.CharField(max_length=50)
    running_time = models.IntegerField()
    rating = models.IntegerField()
    
    def __unicode__(self):
        return "Movie: %s" % self.title


In admin.py:
---------------
from django.contrib import admin
from django.contrib.contenttypes.generic import GenericTabularInline
from foo.models import *

class BookItemAdmin(GenericTabularInline):
    model = BookItem
    
class MovieItemAdmin(GenericTabularInline):
    model = MovieItem

class MyCartAdmin(admin.ModelAdmin):
    inlines = (
        MovieItemAdmin,
        BookItemAdmin,
    )

admin.site.register(ShoppingCart, MyCartAdmin)







I created a Shopping Cart object, and populated the items. Then I went to the shell:

>>> from foo.models import *
>>> s = ShoppingCart.objects.all()[0]
>>> s.order_items.all()
[<GenericItem: GenericItem object>, <GenericItem: GenericItem object>]
>>> o = s.order_items.all()[0]
>>> o.content_object
<ShoppingCart: ShoppingCart object>


WTF? This *should* be returning one of either MovieItem or BookItem should it not?