Commit 2179e5a2 authored by Tim Graham's avatar Tim Graham
Browse files

[1.8.x] Fixed #25715 -- Fixed Model.refresh_from_db() with ForeignKey w/on_delete=SET_NULL. 

Backport of 54e2e688 from master
parent bc8bae0b

django/db/models/base.py

+1 −1
Original line number Diff line number Diff line
@@ -630,7 +630,7 @@ class Model(six.with_metaclass(ModelBase)): 
                rel_instance = getattr(self, field.get_cache_name())

                local_val = getattr(db_instance, field.attname)

                related_val = None if rel_instance is None else getattr(rel_instance, field.related_field.attname)

                if local_val != related_val:

                if local_val != related_val or (local_val is None and related_val is None):

                    del self.__dict__[field.get_cache_name()]

        self._state.db = db_instance._state.db

docs/releases/1.8.7.txt

+3 −0
Original line number Diff line number Diff line
@@ -36,3 +36,6 @@ Bugfixes 
  :class:`~django.contrib.postgres.fields.DateTimeRangeField` (:ticket:`24937`).



* Fixed the exact lookup of ``ArrayField`` (:ticket:`25666`).



* Fixed ``Model.refresh_from_db()`` updating of ``ForeignKey`` fields with

  ``on_delete=models.SET_NULL`` (:ticket:`25715`).

tests/basic/models.py

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ class ArticleSelectOnSave(Article): 
class SelfRef(models.Model):

    selfref = models.ForeignKey('self', null=True, blank=True,

                                related_name='+')

    article = models.ForeignKey(Article, on_delete=models.SET_NULL, null=True, blank=True)



    def __str__(self):

        # This method intentionally doesn't work for all cases - part

tests/basic/tests.py

+11 −0
Original line number Diff line number Diff line
@@ -767,6 +767,17 @@ class ModelRefreshTests(TestCase): 
        self.assertEqual(a2.pub_date, pub_date)

        self.assertEqual(a2._state.db, "default")



    def test_refresh_fk_on_delete_set_null(self):

        a = Article.objects.create(

            headline='Parrot programs in Python',

            pub_date=datetime(2005, 7, 28),

        )

        s1 = SelfRef.objects.create(article=a)

        a.delete()

        s1.refresh_from_db()

        self.assertIsNone(s1.article_id)

        self.assertIsNone(s1.article)



    def test_refresh_no_fields(self):

        a = Article.objects.create(pub_date=self._truncate_ms(datetime.now()))

        with self.assertNumQueries(0):