Fixed #28586 -- Added model field fetch modes.

May your database queries be much reduced with minimal effort.

co-authored-by: Andreas Pelme <andreas@pelme.se>
co-authored-by: Simon Charette <charette.s@gmail.com>
co-authored-by: Jacob Walls <jacobtylerwalls@gmail.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/tests/one_to_one/tests.py b/tests/one_to_one/tests.py
index d9bcb5d4dc..da7bd992c0 100644
--- a/tests/one_to_one/tests.py
+++ b/tests/one_to_one/tests.py
@@ -1,4 +1,6 @@
+from django.core.exceptions import FieldFetchBlocked
 from django.db import IntegrityError, connection, transaction
+from django.db.models import FETCH_PEERS, RAISE
 from django.test import TestCase
 
 from .models import (
@@ -619,3 +621,39 @@ class OneToOneTests(TestCase):
                 instances=places,
                 querysets=[Bar.objects.all(), Bar.objects.all()],
             )
+
+    def test_fetch_mode_fetch_peers_forward(self):
+        Restaurant.objects.create(
+            place=self.p2, serves_hot_dogs=True, serves_pizza=False
+        )
+        r1, r2 = Restaurant.objects.fetch_mode(FETCH_PEERS)
+        with self.assertNumQueries(1):
+            r1.place
+        with self.assertNumQueries(0):
+            r2.place
+
+    def test_fetch_mode_fetch_peers_reverse(self):
+        Restaurant.objects.create(
+            place=self.p2, serves_hot_dogs=True, serves_pizza=False
+        )
+        p1, p2 = Place.objects.fetch_mode(FETCH_PEERS)
+        with self.assertNumQueries(1):
+            p1.restaurant
+        with self.assertNumQueries(0):
+            p2.restaurant
+
+    def test_fetch_mode_raise_forward(self):
+        r = Restaurant.objects.fetch_mode(RAISE).get(pk=self.r1.pk)
+        msg = "Fetching of Restaurant.place blocked."
+        with self.assertRaisesMessage(FieldFetchBlocked, msg) as cm:
+            r.place
+        self.assertIsNone(cm.exception.__cause__)
+        self.assertTrue(cm.exception.__suppress_context__)
+
+    def test_fetch_mode_raise_reverse(self):
+        p = Place.objects.fetch_mode(RAISE).get(pk=self.p1.pk)
+        msg = "Fetching of Place.restaurant blocked."
+        with self.assertRaisesMessage(FieldFetchBlocked, msg) as cm:
+            p.restaurant
+        self.assertIsNone(cm.exception.__cause__)
+        self.assertTrue(cm.exception.__suppress_context__)