id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
24578	prepare_database_save breaks some OneToOneField's in 1.8	dxiao2003	Tim Graham	"With 1.8 the following doesn't work:

{{{
# models.py
from django.db import models

class A(models.Model):
    pass

class Aprime(models.Model):

    original = models.OneToOneField(A, primary_key=True)

class B(models.Model):
    aprime = models.ForeignKey(Aprime)

# tests.py

from django.test import TestCase

from models import *

class TestTestCase(TestCase):

    def test_ref(self):
        a_one = A.objects.create()
        a_two = A.objects.create()

        self.assertNotEqual(a_one, a_two)

        aprime = Aprime.objects.create(original=a_one)
        aprime2 = Aprime.objects.create(original=a_two)

        b = B.objects.create(aprime=aprime)

        self.assertEqual(b.aprime, aprime)

        B.objects.update(aprime=aprime2)

        b = B.objects.get(pk=b.id)

        self.assertEqual(b.aprime, aprime2)
}}}

This throws a `InterfaceError: Error binding parameter 0 - probably unsupported type.` when calling `B.objects.update(aprime=aprime2)`.

The bug disappears when overriding `prepare_database_save` to just return `self.pk` instead of `getattr(self, field.rel.field_name)`.  (This was the behavior as of 1.7 and the bug does not occur there.)

Not sure why `prepare_database_save` was modified but this bug actually affects a project of mine so would suggest rolling back to the 1.7 version."	Bug	closed	Database layer (models, ORM)	1.8	Release blocker	fixed			Accepted	1	0	0	0	0	0