Ticket #8076: patch_for_getnext_with_subclasstests.diff

django/db/models/base.py

@@ -438 +438 @@
         op = is_next and 'gt' or 'lt'
         order = not is_next and '-' or ''
         param = smart_str(getattr(self, field.attname))
+        # Hackish, but add another __pk lookup if the model is a child model
+        pk_string = self.__class__._meta.parents and 'pk__pk__' or 'pk__'
         q = Q(**{'%s__%s' % (field.name, op): param})
-        q = q|Q(**{field.name: param, 'pk__%s' % op: self.pk})
+        q = q|Q(**{field.name: param, '%s%s' % (pk_string,op): self.pk})
         qs = self.__class__._default_manager.filter(**kwargs).filter(q).order_by('%s%s' % (order, field.name), '%spk' % order)
         try:
             return qs[0]

tests/modeltests/lookup/models.py

@@ -16 +16 @@
     def __unicode__(self):
         return self.headline
 
+class ParentModel(models.Model):
+    headline = models.CharField(max_length=100)
+    pub_date = models.DateTimeField()
+    def __unicode__(self):
+        return self.headline
+
+class ChildModel(ParentModel):
+    stupid = models.CharField(max_length=100)
+
 __test__ = {'API_TESTS':r"""
 # Create a couple of Articles.
 >>> from datetime import datetime
@@ -34 +43 @@
 >>> a7 = Article(headline='Article 7', pub_date=datetime(2005, 7, 27))
 >>> a7.save()
 
+# Create some childclass objects
+>>> c1 = ChildModel(headline='ArticleChild 1', pub_date=datetime(2005, 8, 1, 3, 0))
+>>> c1.save()
+>>> c2 = ChildModel(headline='ArticleChild 2', pub_date=datetime(2005, 8, 1, 10, 0))
+>>> c2.save()
+>>> c3 = ChildModel(headline='ArticleChild 3', pub_date=datetime(2005, 8, 2))
+>>> c3.save()
+
 # text matching tests for PostgreSQL 8.3
 >>> Article.objects.filter(id__iexact='1')
 [<Article: Article 1>]
@@ -234 +251 @@
 >>> a2.get_previous_by_pub_date()
 <Article: Article 1>
 
+# test subclassed models for get previous/next, too
+>>> c1.get_next_by_pub_date()
+<ChildModel: ArticleChild 2>
+>>> c2.get_next_by_pub_date()
+<ChildModel: ArticleChild 3>
+>>> c3.get_next_by_pub_date()
+Traceback (most recent call last):
+    ...
+DoesNotExist: ChildModel matching query does not exist.
+>>> c3.get_previous_by_pub_date()
+<ChildModel: ArticleChild 2>
+>>> c2.get_previous_by_pub_date()
+<ChildModel: ArticleChild 1>
+>>> c1.get_previous_by_pub_date()
+Traceback (most recent call last):
+    ...
+DoesNotExist: ChildModel matching query does not exist.
+
 # Underscores and percent signs have special meaning in the underlying
 # SQL code, but Django handles the quoting of them automatically.
 >>> a8 = Article(headline='Article_ with underscore', pub_date=datetime(2005, 11, 20))