Fixed #33772 -- Added QuerySet.first()/last() error message on unordered queryset with aggregation.

tests/get_earliest_or_latest/models.py

@@ -16,6 +16,11 @@ class Person(models.Model):
     # Note that this model doesn't have "get_latest_by" set.
 
 
+class Comment(models.Model):
+    article = models.ForeignKey(Article, on_delete=models.CASCADE)
+    likes_count = models.PositiveIntegerField()
+
+
 # Ticket #23555 - model with an intentionally broken QuerySet.__iter__ method.
 
 

tests/get_earliest_or_latest/tests.py

@@ -1,8 +1,9 @@
 from datetime import datetime
 
+from django.db.models import Avg
 from django.test import TestCase
 
-from .models import Article, IndexErrorArticle, Person
+from .models import Article, Comment, IndexErrorArticle, Person
 
 
 class EarliestOrLatestTests(TestCase):
@@ -245,3 +246,21 @@ class TestFirstLast(TestCase):
             expire_date=datetime(2005, 9, 1),
         )
         check()
+
+    def test_first_last_unordered_qs_aggregation_error(self):
+        a1 = Article.objects.create(
+            headline="Article 1",
+            pub_date=datetime(2005, 7, 26),
+            expire_date=datetime(2005, 9, 1),
+        )
+        Comment.objects.create(article=a1, likes_count=5)
+
+        qs = Comment.objects.values("article").annotate(avg_likes=Avg("likes_count"))
+        msg = (
+            "Cannot use QuerySet.%s() on an unordered queryset performing aggregation. "
+            "Add an ordering with order_by()."
+        )
+        with self.assertRaisesMessage(TypeError, msg % "first"):
+            qs.first()
+        with self.assertRaisesMessage(TypeError, msg % "last"):
+            qs.last()