How to make a TastyPie API with nested resources.

api.py

class ArticleResource(ModelResource):
    class Meta:
        authentication  = Authentication()
        authorization   = DjangoAuthorization()
        queryset        = Article.objects.all()


class CategoryResource(ModelResource):
    articles = fields.ToManyField('locations.api.Articles', 'articles', full=True)

    class Meta:
        authentication  = Authentication()
        authorization   = DjangoAuthorization()
        queryset        = Category.objects.all()

models.py

class Article(models.Model):
    category = models.ForeignKey('Category')
    title = models.CharField(max_length=50)
    content = models.TextField()

class Category(models.Model):
    name = models.CharField(max_length=50)

urls.py

v1_api = Api(api_name='v1')
v1_api.register(ArticleResource())
v1_api.register(CategoryResource())


urlpatterns = patterns('',
    url(r'^api/', include(v1_api.urls)),
)