Fixed #8291 -- Allowed 'pk' to be used as an ordering option in `Model.Meta`. Thanks to peterd12 for the report and to evan_schulz, gruszczy, frog32 and David Gouldin for their work on the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17445 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/core/management/validation.py

@@ -283,6 +283,11 @@ def get_validation_errors(outfile, app=None):
                 # this format would be nice, but it's a little fiddly).
                 if '__' in field_name:
                     continue
+                # Skip ordering on pk, this is always a valid order_by field
+                # but is an alias and therefore won't be found by
+                # opts.get_field.
+                if field_name == 'pk':
+                    continue
                 try:
                     opts.get_field(field_name, many_to_many=False)
                 except models.FieldDoesNotExist:

tests/modeltests/invalid_models/invalid_models/models.py

@@ -233,6 +233,15 @@ class UnicodeForeignKeys(models.Model):
 class PrimaryKeyNull(models.Model):
     my_pk_field = models.IntegerField(primary_key=True, null=True)
 
+class OrderByPKModel(models.Model):
+    """
+    Model to test that ordering by pk passes validation.
+    Refs #8291
+    """
+    name = models.CharField(max_length=100, blank=True)
+
+    class Meta:
+        ordering = ('pk',)
 
 model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute that is a positive integer.
 invalid_models.fielderrors: "charfield2": CharFields require a "max_length" attribute that is a positive integer.

tests/modeltests/ordering/models.py

@@ -24,3 +24,12 @@ class Article(models.Model):
 
     def __unicode__(self):
         return self.headline
+
+class ArticlePKOrdering(models.Model):
+    headline = models.CharField(max_length=100)
+    pub_date = models.DateTimeField()
+    class Meta:
+        ordering = ('-pk',)
+
+    def __unicode__(self):
+        return self.headline

tests/modeltests/ordering/tests.py

@@ -5,7 +5,7 @@ from operator import attrgetter
 
 from django.test import TestCase
 
-from .models import Article
+from .models import Article, ArticlePKOrdering
 
 
 class OrderingTests(TestCase):
@@ -137,3 +137,31 @@ class OrderingTests(TestCase):
             ],
             attrgetter("headline")
         )
+
+    def test_order_by_pk(self):
+        """
+        Ensure that 'pk' works as an ordering option in Meta.
+        Refs #8291.
+        """
+        a1 = ArticlePKOrdering.objects.create(
+            pk=1, headline="Article 1", pub_date=datetime(2005, 7, 26)
+        )
+        a2 = ArticlePKOrdering.objects.create(
+            pk=2, headline="Article 2", pub_date=datetime(2005, 7, 27)
+        )
+        a3 = ArticlePKOrdering.objects.create(
+            pk=3, headline="Article 3", pub_date=datetime(2005, 7, 27)
+        )
+        a4 = ArticlePKOrdering.objects.create(
+            pk=4, headline="Article 4", pub_date=datetime(2005, 7, 28)
+        )
+
+        self.assertQuerysetEqual(
+            ArticlePKOrdering.objects.all(), [
+                "Article 4",
+                "Article 3",
+                "Article 2",
+                "Article 1",
+            ],
+            attrgetter("headline")
+        )