Added a `QuerySet.ordered` property to check if a queryset is already ordered. Refs #10163.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10623 bcc190cf-cafb-0310-a4f2-bffc1f526a37

3 files changed, 50 insertions, 0 deletions

diff --git a/django/db/models/query.py b/django/db/models/query.py
index 9323e9b36b..5567b3227d 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -615,7 +615,24 @@ class QuerySet(object):
         clone = self._clone()
         clone.query.add_immediate_loading(fields)
         return clone
+        
+    ###################################
+    # PUBLIC INTROSPECTION ATTRIBUTES #
+    ###################################
 
+    def ordered(self):
+        """
+        Returns True if the QuerySet is ordered -- i.e. has an order_by()
+        clause or a default ordering on the model.
+        """
+        if self.query.extra_order_by or self.query.order_by:
+            return True
+        elif self.query.default_ordering and self.query.model._meta.ordering:
+            return True
+        else:
+            return False
+    ordered = property(ordered)
+    
     ###################
     # PRIVATE METHODS #
     ###################
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt
index fa58060916..6c08fe079e 100644
--- a/docs/ref/models/querysets.txt
+++ b/docs/ref/models/querysets.txt
@@ -268,6 +268,12 @@ There's no way to specify whether ordering should be case sensitive. With
 respect to case-sensitivity, Django will order results however your database
 backend normally orders them.
 
+.. versionadded:: 1.1
+
+You can tell if a query is ordered or not by checking the
+:attr:`QuerySet.ordered` attribute, which will be ``True`` if the
+``QuerySet`` has been ordered in any way.
+
 ``reverse()``
 ~~~~~~~~~~~~~
 
diff --git a/tests/regressiontests/queries/tests.py b/tests/regressiontests/queries/tests.py
new file mode 100644
index 0000000000..5699b60241
--- /dev/null
+++ b/tests/regressiontests/queries/tests.py
@@ -0,0 +1,27 @@
+import unittest
+from models import Tag, Annotation
+from django.db.models import Count
+
+class QuerysetOrderedTests(unittest.TestCase):
+    """
+    Tests for the Queryset.ordered attribute.
+    """
+    
+    def test_no_default_or_explicit_ordering(self):
+        self.assertEqual(Annotation.objects.all().ordered, False)
+
+    def test_cleared_default_ordering(self):
+        self.assertEqual(Tag.objects.all().ordered, True)
+        self.assertEqual(Tag.objects.all().order_by().ordered, False)
+        
+    def test_explicit_ordering(self):
+        self.assertEqual(Annotation.objects.all().order_by('id').ordered, True)
+        
+    def test_order_by_extra(self):
+        self.assertEqual(Annotation.objects.all().extra(order_by=['id']).ordered, True)
+        
+    def test_annotated_ordering(self):
+        qs = Annotation.objects.annotate(num_notes=Count('notes'))
+        self.assertEqual(qs.ordered, False)
+        self.assertEqual(qs.order_by('num_notes').ordered, True)
+        
\ No newline at end of file