Calling alias after values_list adds the aliased value to the result set

[OutOfFocus4]

ORM calls that worked prior to Django 5.2 now return different results or outright fail in Django 5.2. I have attached a file with proof-of-concept tests.

The first issue I noticed is that calling alias on after values_list adds the aliased value to the result set. I believe the root of this error is in django/db/models/sql/query.py lines 1224 and 1225:

        if self.selected:
            self.selected[alias] = alias

This code adds the alias to selected regardless of the value of the select parameter.

Another issue I found causes queryset evaluation to raise an AttributeError if the database backend supports SELECT ... FOR UPDATE. The following code:

with atomic():
    values = (
        User.objects.select_for_update(of=("self",))
        .values_list(
            Concat(F("first_name"), Value(" "), F("last_name")), "email"
        )
        .get(pk=12)
    )

will fail with a stacktrace ending in AttributeError: 'Concat' object has no attribute 'target' using the postgresql DB backend.

[Simon Charette]

Regression in #28900 (65ad4ade74dc9208b9d686a451cd6045df0c9c3a)

Thanks for the detailed report.

The first issue I noticed is that calling alias on after values_list adds the aliased value to the result set. I believe the root of this error is in django/db/models/sql/query.py lines 1224 and 1225:
...
This code adds the alias to selected regardless of the value of the select parameter.

That's effectively the origin of the problem, thanks for investigating.

Currently looking into the second one with select_for_update.

[Sarah Boyce]

Thank you for the report

Simon you're too quick!

tests/queries/tests.py

@@ -7 +7 @@
 from django.core.exceptions import EmptyResultSet, FieldError, FullResultSet
 from django.db import DEFAULT_DB_ALIAS, connection
 from django.db.models import CharField, Count, Exists, F, Max, OuterRef, Q
-from django.db.models.expressions import RawSQL
+from django.db.models.expressions import RawSQL, Value
 from django.db.models.functions import ExtractYear, Length, LTrim
 from django.db.models.sql.constants import LOUTER
 from django.db.models.sql.where import AND, OR, NothingNode, WhereNode
@@ -2737 +2737 @@
         qs = qs.values_list("num")
         self.assertSequenceEqual(qs, [(72,)])
 
+    def test_values_list_with_alias(self):
+        qs = Number.objects.values_list("num").alias(extra=Value(1))
+        self.assertSequenceEqual(qs, [(72,)])
+
     def test_flat_extra_values_list(self):
         # testing for ticket 14930 issues

Replicated the alias issue and confirmed it's a regression in 65ad4ade74dc9208b9d686a451cd6045df0c9c3a
If select_for_update is a separate issue, we should create a separate ticket

[Sarah Boyce]

Replicated the second issue, also a regression in 65ad4ade74dc9208b9d686a451cd6045df0c9c3a

tests/select_for_update/tests.py

@@ -13 +13 @@
     router,
     transaction,
 )
+from django.db.models import F, Value
+from django.db.models.functions import Concat
 from django.test import (
     TransactionTestCase,
     override_settings,
@@ -122 +124 @@
             list(Person.objects.select_for_update(no_key=True))
         self.assertIs(self.has_for_update_sql(ctx.captured_queries, no_key=True), True)
 
+    @skipUnlessDBFeature("has_select_for_update_of")
+    def test_for_update_of_values_list(self):
+        with transaction.atomic():
+            values = (
+                Person.objects.select_for_update(
+                    of=("self",),
+                )
+                .values_list(Concat(Value("Dr. "), F("name")), "born")
+            ).get(pk=self.person.pk)
+        self.assertTupleEqual(values, ("Dr. Reinhardt", self.city1.pk))
+
     @skipUnlessDBFeature("has_select_for_update_of")

[Simon Charette]

Thanks for the triage Sarah, I'll create a ticket for the second one.

Here's ​a PR for the alias issue Jeff. I gave you co-author attribute since you pointed at the exact solution and provided tests but I can remove it if you'd prefer just LMK on Github.

[Simon Charette]

Moved the select_for_update issue to #36301.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 12b771a1:

Fixed #36299 -- Prevented field selection on QuerySet.alias() after values().

Regression in 65ad4ade74dc9208b9d686a451cd6045df0c9c3a.

Refs #28900.

Thanks Jeff Iadarola for the report and tests.

Co-Authored-By: OutOfFocus4 <jeff.iadarola@…>

[Mariusz Felisiak <felisiak.mariusz@…>]

In cd1aa54f:

[5.2.x] Fixed #36299 -- Prevented field selection on QuerySet.alias() after values().

Regression in 65ad4ade74dc9208b9d686a451cd6045df0c9c3a.

Refs #28900.

Thanks Jeff Iadarola for the report and tests.

Co-Authored-By: OutOfFocus4 <jeff.iadarola@…>

Backport of 12b771a1ec4bbfe82405176f5601e6441855a303 from main