mirror of
https://github.com/django/django.git
synced 2025-10-31 09:41:08 +00:00
b6c356b7bb
This commit tackles a couple of issues. First, in certain cases there were some mixups if field.attname or field.name should be deferred. Field.attname is now always used. Another issue tackled is a case where field is both deferred by .only(), and selected by select_related. This case is now an error. A lot of thanks to koniiiik (Michal Petrucha) for the patch, and to Andrei Antoukh for review.
186 lines
7.2 KiB
Python
186 lines
7.2 KiB
Python
from __future__ import absolute_import
|
|
|
|
from django.db.models.query_utils import DeferredAttribute, InvalidQuery
|
|
from django.test import TestCase
|
|
|
|
from .models import Secondary, Primary, Child, BigChild, ChildProxy
|
|
|
|
|
|
class DeferTests(TestCase):
|
|
def assert_delayed(self, obj, num):
|
|
count = 0
|
|
for field in obj._meta.fields:
|
|
if isinstance(obj.__class__.__dict__.get(field.attname),
|
|
DeferredAttribute):
|
|
count += 1
|
|
self.assertEqual(count, num)
|
|
|
|
def test_defer(self):
|
|
# To all outward appearances, instances with deferred fields look the
|
|
# same as normal instances when we examine attribute values. Therefore
|
|
# we test for the number of deferred fields on returned instances (by
|
|
# poking at the internals), as a way to observe what is going on.
|
|
|
|
s1 = Secondary.objects.create(first="x1", second="y1")
|
|
p1 = Primary.objects.create(name="p1", value="xx", related=s1)
|
|
|
|
qs = Primary.objects.all()
|
|
|
|
self.assert_delayed(qs.defer("name")[0], 1)
|
|
self.assert_delayed(qs.only("name")[0], 2)
|
|
self.assert_delayed(qs.defer("related__first")[0], 0)
|
|
|
|
# Using 'pk' with only() should result in 3 deferred fields, namely all
|
|
# of them except the model's primary key see #15494
|
|
self.assert_delayed(qs.only("pk")[0], 3)
|
|
|
|
obj = qs.select_related().only("related__first")[0]
|
|
self.assert_delayed(obj, 2)
|
|
|
|
self.assertEqual(obj.related_id, s1.pk)
|
|
|
|
# You can use 'pk' with reverse foreign key lookups.
|
|
self.assert_delayed(s1.primary_set.all().only('pk')[0], 3)
|
|
|
|
self.assert_delayed(qs.defer("name").extra(select={"a": 1})[0], 1)
|
|
self.assert_delayed(qs.extra(select={"a": 1}).defer("name")[0], 1)
|
|
self.assert_delayed(qs.defer("name").defer("value")[0], 2)
|
|
self.assert_delayed(qs.only("name").only("value")[0], 2)
|
|
self.assert_delayed(qs.only("name").defer("value")[0], 2)
|
|
self.assert_delayed(qs.only("name", "value").defer("value")[0], 2)
|
|
self.assert_delayed(qs.defer("name").only("value")[0], 2)
|
|
|
|
obj = qs.only()[0]
|
|
self.assert_delayed(qs.defer(None)[0], 0)
|
|
self.assert_delayed(qs.only("name").defer(None)[0], 0)
|
|
|
|
# User values() won't defer anything (you get the full list of
|
|
# dictionaries back), but it still works.
|
|
self.assertEqual(qs.defer("name").values()[0], {
|
|
"id": p1.id,
|
|
"name": "p1",
|
|
"value": "xx",
|
|
"related_id": s1.id,
|
|
})
|
|
self.assertEqual(qs.only("name").values()[0], {
|
|
"id": p1.id,
|
|
"name": "p1",
|
|
"value": "xx",
|
|
"related_id": s1.id,
|
|
})
|
|
|
|
# Using defer() and only() with get() is also valid.
|
|
self.assert_delayed(qs.defer("name").get(pk=p1.pk), 1)
|
|
self.assert_delayed(qs.only("name").get(pk=p1.pk), 2)
|
|
|
|
# When we defer a field and also select_related it, the query is
|
|
# invalid and raises an exception.
|
|
with self.assertRaises(InvalidQuery):
|
|
qs.only("name").select_related("related")[0]
|
|
with self.assertRaises(InvalidQuery):
|
|
qs.defer("related").select_related("related")[0]
|
|
|
|
# With a depth-based select_related, all deferred ForeignKeys are
|
|
# deferred instead of traversed.
|
|
with self.assertNumQueries(3):
|
|
obj = qs.defer("related").select_related()[0]
|
|
self.assert_delayed(obj, 1)
|
|
self.assertEqual(obj.related.id, s1.pk)
|
|
|
|
# Saving models with deferred fields is possible (but inefficient,
|
|
# since every field has to be retrieved first).
|
|
obj = Primary.objects.defer("value").get(name="p1")
|
|
obj.name = "a new name"
|
|
obj.save()
|
|
self.assertQuerysetEqual(
|
|
Primary.objects.all(), [
|
|
"a new name",
|
|
],
|
|
lambda p: p.name
|
|
)
|
|
|
|
# Regression for #10572 - A subclass with no extra fields can defer
|
|
# fields from the base class
|
|
Child.objects.create(name="c1", value="foo", related=s1)
|
|
# You can defer a field on a baseclass when the subclass has no fields
|
|
obj = Child.objects.defer("value").get(name="c1")
|
|
self.assert_delayed(obj, 1)
|
|
self.assertEqual(obj.name, "c1")
|
|
self.assertEqual(obj.value, "foo")
|
|
obj.name = "c2"
|
|
obj.save()
|
|
|
|
# You can retrive a single column on a base class with no fields
|
|
obj = Child.objects.only("name").get(name="c2")
|
|
self.assert_delayed(obj, 3)
|
|
self.assertEqual(obj.name, "c2")
|
|
self.assertEqual(obj.value, "foo")
|
|
obj.name = "cc"
|
|
obj.save()
|
|
|
|
BigChild.objects.create(name="b1", value="foo", related=s1, other="bar")
|
|
# You can defer a field on a baseclass
|
|
obj = BigChild.objects.defer("value").get(name="b1")
|
|
self.assert_delayed(obj, 1)
|
|
self.assertEqual(obj.name, "b1")
|
|
self.assertEqual(obj.value, "foo")
|
|
self.assertEqual(obj.other, "bar")
|
|
obj.name = "b2"
|
|
obj.save()
|
|
|
|
# You can defer a field on a subclass
|
|
obj = BigChild.objects.defer("other").get(name="b2")
|
|
self.assert_delayed(obj, 1)
|
|
self.assertEqual(obj.name, "b2")
|
|
self.assertEqual(obj.value, "foo")
|
|
self.assertEqual(obj.other, "bar")
|
|
obj.name = "b3"
|
|
obj.save()
|
|
|
|
# You can retrieve a single field on a baseclass
|
|
obj = BigChild.objects.only("name").get(name="b3")
|
|
self.assert_delayed(obj, 4)
|
|
self.assertEqual(obj.name, "b3")
|
|
self.assertEqual(obj.value, "foo")
|
|
self.assertEqual(obj.other, "bar")
|
|
obj.name = "b4"
|
|
obj.save()
|
|
|
|
# You can retrieve a single field on a baseclass
|
|
obj = BigChild.objects.only("other").get(name="b4")
|
|
self.assert_delayed(obj, 4)
|
|
self.assertEqual(obj.name, "b4")
|
|
self.assertEqual(obj.value, "foo")
|
|
self.assertEqual(obj.other, "bar")
|
|
obj.name = "bb"
|
|
obj.save()
|
|
|
|
def test_defer_proxy(self):
|
|
"""
|
|
Ensure select_related together with only on a proxy model behaves
|
|
as expected. See #17876.
|
|
"""
|
|
related = Secondary.objects.create(first='x1', second='x2')
|
|
ChildProxy.objects.create(name='p1', value='xx', related=related)
|
|
children = ChildProxy.objects.all().select_related().only('id', 'name')
|
|
self.assertEqual(len(children), 1)
|
|
child = children[0]
|
|
self.assert_delayed(child, 2)
|
|
self.assertEqual(child.name, 'p1')
|
|
self.assertEqual(child.value, 'xx')
|
|
|
|
def test_defer_inheritance_pk_chaining(self):
|
|
"""
|
|
When an inherited model is fetched from the DB, its PK is also fetched.
|
|
When getting the PK of the parent model it is useful to use the already
|
|
fetched parent model PK if it happens to be available. Tests that this
|
|
is done.
|
|
"""
|
|
s1 = Secondary.objects.create(first="x1", second="y1")
|
|
bc = BigChild.objects.create(name="b1", value="foo", related=s1,
|
|
other="bar")
|
|
bc_deferred = BigChild.objects.only('name').get(pk=bc.pk)
|
|
with self.assertNumQueries(0):
|
|
bc_deferred.id
|
|
self.assertEqual(bc_deferred.pk, bc_deferred.id)
|