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Code Issues 32 Releases Wiki Activity

Fixed #28586 -- Added model field fetch modes.

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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>
This commit is contained in:
Adam Johnson
2023-11-29 09:35:34 +00:00
committed by Jacob Walls
parent f6bd90c840
commit e097e8a12f
24 changed files with 682 additions and 73 deletions
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68
tests/defer/tests.py
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@@ -1,4 +1,5 @@
from django.core.exceptions import FieldDoesNotExist, FieldError
from django.core.exceptions import FieldDoesNotExist, FieldError, FieldFetchBlocked
from django.db.models import FETCH_PEERS, RAISE
from django.test import SimpleTestCase, TestCase
from .models import (
@@ -29,6 +30,7 @@ class DeferTests(AssertionMixin, TestCase):
def setUpTestData(cls):
cls.s1 = Secondary.objects.create(first="x1", second="y1")
cls.p1 = Primary.objects.create(name="p1", value="xx", related=cls.s1)
cls.p2 = Primary.objects.create(name="p2", value="yy", related=cls.s1)
def test_defer(self):
qs = Primary.objects.all()
@@ -141,7 +143,6 @@ class DeferTests(AssertionMixin, TestCase):
def test_saving_object_with_deferred_field(self):
# Saving models with deferred fields is possible (but inefficient,
# since every field has to be retrieved first).
Primary.objects.create(name="p2", value="xy", related=self.s1)
obj = Primary.objects.defer("value").get(name="p2")
obj.name = "a new name"
obj.save()
@@ -181,10 +182,71 @@ class DeferTests(AssertionMixin, TestCase):
self.assertEqual(obj.name, "adonis")
def test_defer_fk_attname(self):
primary = Primary.objects.defer("related_id").get()
primary = Primary.objects.defer("related_id").get(name="p1")
with self.assertNumQueries(1):
self.assertEqual(primary.related_id, self.p1.related_id)
def test_only_fetch_mode_fetch_peers(self):
p1, p2 = Primary.objects.fetch_mode(FETCH_PEERS).only("name")
with self.assertNumQueries(1):
p1.value
with self.assertNumQueries(0):
p2.value
def test_only_fetch_mode_fetch_peers_single(self):
p1 = Primary.objects.fetch_mode(FETCH_PEERS).only("name").get(name="p1")
with self.assertNumQueries(1):
p1.value
def test_defer_fetch_mode_fetch_peers(self):
p1, p2 = Primary.objects.fetch_mode(FETCH_PEERS).defer("value")
with self.assertNumQueries(1):
p1.value
with self.assertNumQueries(0):
p2.value
def test_defer_fetch_mode_fetch_peers_single(self):
p1 = Primary.objects.fetch_mode(FETCH_PEERS).defer("value").get(name="p1")
with self.assertNumQueries(1):
p1.value
def test_only_fetch_mode_raise(self):
p1 = Primary.objects.fetch_mode(RAISE).only("name").get(name="p1")
msg = "Fetching of Primary.value blocked."
with self.assertRaisesMessage(FieldFetchBlocked, msg) as cm:
p1.value
self.assertIsNone(cm.exception.__cause__)
self.assertTrue(cm.exception.__suppress_context__)
def test_defer_fetch_mode_raise(self):
p1 = Primary.objects.fetch_mode(RAISE).defer("value").get(name="p1")
msg = "Fetching of Primary.value blocked."
with self.assertRaisesMessage(FieldFetchBlocked, msg) as cm:
p1.value
self.assertIsNone(cm.exception.__cause__)
self.assertTrue(cm.exception.__suppress_context__)
class DeferOtherDatabaseTests(TestCase):
databases = {"other"}
@classmethod
def setUpTestData(cls):
cls.s1 = Secondary.objects.using("other").create(first="x1", second="y1")
cls.p1 = Primary.objects.using("other").create(
name="p1", value="xx", related=cls.s1
)
cls.p2 = Primary.objects.using("other").create(
name="p2", value="yy", related=cls.s1
)
def test_defer_fetch_mode_fetch_peers(self):
p1, p2 = Primary.objects.using("other").fetch_mode(FETCH_PEERS).defer("value")
with self.assertNumQueries(1, using="other"):
p1.value
with self.assertNumQueries(0, using="other"):
p2.value
class BigChildDeferTests(AssertionMixin, TestCase):
@classmethod