[1.8.x] Fixed #24578 -- Fixed crash with QuerySet.update() on FK to O2O fields.

Thanks Anssi Kääriäinen for review.

Backport of 10b4c010ab2cdaa6ba8bfaec3e3540299ea77be from master

1 files changed, 1 insertions, 1 deletions

diff --git a/django/db/models/base.py b/django/db/models/base.py
index 4b51ca85d8..86ba01ffcc 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -912,7 +912,7 @@ class Model(six.with_metaclass(ModelBase)):
     def prepare_database_save(self, field):
         if self.pk is None:
             raise ValueError("Unsaved model instance %r cannot be used in an ORM query." % self)
-        return getattr(self, field.rel.field_name)
+        return getattr(self, field.rel.get_related_field().attname)
 
     def clean(self):
         """