Fix #13864: Removed database error raised when force_update is requsted on save…

Fix #13864: Removed database error raised when force_update is requsted on save of an inherited model with no fields of its own. Thanks fva, gregmuellegger, and markb1.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17088 bcc190cf-cafb-0310-a4f2-bffc1f526a37

AUTHORS

@@ -87,6 +87,7 @@ answer newbie questions, and generally made Django that much better:
     Julian Bez
     Arvis Bickovskis <viestards.lists@gmail.com>
     Natalia Bidart <nataliabidart@gmail.com>
+    Mark Biggers <biggers@utsl.com>
     Paul Bissex <http://e-scribe.com/>
     Simon Blanchard
     David Blewett <david@dawninglight.net>

django/db/models/base.py

@@ -526,9 +526,10 @@ class Model(object):
                     # It does already exist, so do an UPDATE.
                     if force_update or non_pks:
                         values = [(f, None, (raw and getattr(self, f.attname) or f.pre_save(self, False))) for f in non_pks]
-                        rows = manager.using(using).filter(pk=pk_val)._update(values)
-                        if force_update and not rows:
-                            raise DatabaseError("Forced update did not affect any rows.")
+                        if values:
+                            rows = manager.using(using).filter(pk=pk_val)._update(values)
+                            if force_update and not rows:
+                                raise DatabaseError("Forced update did not affect any rows.")
                 else:
                     record_exists = False
             if not pk_set or not record_exists:

tests/modeltests/force_insert_update/models.py

@@ -9,6 +9,16 @@ class Counter(models.Model):
     name = models.CharField(max_length = 10)
     value = models.IntegerField()
 
+class InheritedCounter(Counter):
+    tag = models.CharField(max_length=10)
+
+class ProxyCounter(Counter):
+    class Meta:
+        proxy = True
+
+class SubCounter(Counter):
+    pass
+
 class WithCustomPK(models.Model):
     name = models.IntegerField(primary_key=True)
     value = models.IntegerField()

tests/modeltests/force_insert_update/tests.py

@@ -3,14 +3,15 @@ from __future__ import absolute_import
 from django.db import transaction, IntegrityError, DatabaseError
 from django.test import TestCase
 
-from .models import Counter, WithCustomPK
+from .models import (Counter, WithCustomPK, InheritedCounter, ProxyCounter,
+                     SubCounter)
 
 
 class ForceTests(TestCase):
     def test_force_update(self):
         c = Counter.objects.create(name="one", value=1)
-        # The normal case
 
+        # The normal case
         c.value = 2
         c.save()
         # Same thing, via an update
@@ -38,3 +39,25 @@ class ForceTests(TestCase):
         # the data isn't in the database already.
         obj = WithCustomPK(name=1, value=1)
         self.assertRaises(DatabaseError, obj.save, force_update=True)
+
+
+class InheritanceTests(TestCase):
+    def test_force_update_on_inherited_model(self):
+        a = InheritedCounter(name="count", value=1, tag="spam")
+        a.save()
+        a.save(force_update=True)
+
+    def test_force_update_on_proxy_model(self):
+        a = ProxyCounter(name="count", value=1)
+        a.save()
+        a.save(force_update=True)
+
+    def test_force_update_on_inherited_model_without_fields(self):
+        '''
+        Issue 13864: force_update fails on subclassed models, if they don't
+        specify custom fields.
+        '''
+        a = SubCounter(name="count", value=1)
+        a.save()
+        a.value = 2
+        a.save(force_update=True)