nested.py

from django.db.models.sql.constants import LOOKUP_SEP
from tastypie.fields import ToOneField
class NestedToOneField(ToOneField):
  def dehydrate(self, bundle):
        try:
            foreign_obj = reduce(lambda obj, attr: getattr(obj, attr), self.attribute.split(LOOKUP_SEP), bundle.obj)
        except ObjectDoesNotExist:
            foreign_obj = None

        if not foreign_obj:
            if not self.null:
                raise ApiFieldError("The model '%r' has an empty attribute '%s' and doesn't allow a null value." % (bundle.obj, self.attribute))

            return None

        self.fk_resource = self.get_related_resource(foreign_obj)
        fk_bundle = Bundle(obj=foreign_obj, request=bundle.request)
        return self.dehydrate_related(fk_bundle, self.fk_resource)

class EntryResource(ModelResource):
    subject = NestedToOneField(SubjectResource,'page__topic__chapter__subject',full=True)
    # Rest like normal