django/tests/defer_regress/tests.py

from operator import attrgetter

from django.contrib.contenttypes.models import ContentType
from django.contrib.sessions.backends.db import SessionStore
from django.db import models
from django.db.models import Count
from django.test import TestCase, ignore_warnings, override_settings
from django.utils.deprecation import RemovedInDjango50Warning

from .models import (
    Base,
    Child,
    Derived,
    Feature,
    Item,
    ItemAndSimpleItem,
    Leaf,
    Location,
    OneToOneItem,
    Proxy,
    ProxyRelated,
    RelatedItem,
    Request,
    ResolveThis,
    SimpleItem,
    SpecialFeature,
)


class DeferRegressionTest(TestCase):
    def test_basic(self):
        # Deferred fields should really be deferred and not accidentally use
        # the field's default value just because they aren't passed to __init__

        Item.objects.create(name="first", value=42)
        obj = Item.objects.only("name", "other_value").get(name="first")
        # Accessing "name" doesn't trigger a new database query. Accessing
        # "value" or "text" should.
        with self.assertNumQueries(0):
            self.assertEqual(obj.name, "first")
            self.assertEqual(obj.other_value, 0)

        with self.assertNumQueries(1):
            self.assertEqual(obj.value, 42)

        with self.assertNumQueries(1):
            self.assertEqual(obj.text, "xyzzy")

        with self.assertNumQueries(0):
            self.assertEqual(obj.text, "xyzzy")

        # Regression test for #10695. Make sure different instances don't
        # inadvertently share data in the deferred descriptor objects.
        i = Item.objects.create(name="no I'm first", value=37)
        items = Item.objects.only("value").order_by("-value")
        self.assertEqual(items[0].name, "first")
        self.assertEqual(items[1].name, "no I'm first")

        RelatedItem.objects.create(item=i)
        r = RelatedItem.objects.defer("item").get()
        self.assertEqual(r.item_id, i.id)
        self.assertEqual(r.item, i)

        # Some further checks for select_related() and inherited model
        # behavior (regression for #10710).
        c1 = Child.objects.create(name="c1", value=42)
        c2 = Child.objects.create(name="c2", value=37)
        Leaf.objects.create(name="l1", child=c1, second_child=c2)

        obj = Leaf.objects.only("name", "child").select_related()[0]
        self.assertEqual(obj.child.name, "c1")

        self.assertQuerysetEqual(
            Leaf.objects.select_related().only("child__name", "second_child__name"),
            [
                "l1",
            ],
            attrgetter("name"),
        )

        # Models instances with deferred fields should still return the same
        # content types as their non-deferred versions (bug #10738).
        ctype = ContentType.objects.get_for_model
        c1 = ctype(Item.objects.all()[0])
        c2 = ctype(Item.objects.defer("name")[0])
        c3 = ctype(Item.objects.only("name")[0])
        self.assertTrue(c1 is c2 is c3)

        # Regression for #10733 - only() can be used on a model with two
        # foreign keys.
        results = Leaf.objects.only("name", "child", "second_child").select_related()
        self.assertEqual(results[0].child.name, "c1")
        self.assertEqual(results[0].second_child.name, "c2")

        results = Leaf.objects.only(
            "name", "child", "second_child", "child__name", "second_child__name"
        ).select_related()
        self.assertEqual(results[0].child.name, "c1")
        self.assertEqual(results[0].second_child.name, "c2")

        # Regression for #16409 - make sure defer() and only() work with annotate()
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count("feature")).defer("name")), list
        )
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count("feature")).only("name")), list
        )

    @ignore_warnings(category=RemovedInDjango50Warning)
    @override_settings(
        SESSION_SERIALIZER="django.contrib.sessions.serializers.PickleSerializer"
    )
    def test_ticket_12163(self):
        # Test for #12163 - Pickling error saving session with unsaved model
        # instances.
        SESSION_KEY = "2b1189a188b44ad18c35e1baac6ceead"

        item = Item()
        item._deferred = False
        s = SessionStore(SESSION_KEY)
        s.clear()
        s["item"] = item
        s.save(must_create=True)

        s = SessionStore(SESSION_KEY)
        s.modified = True
        s.save()

        i2 = s["item"]
        self.assertFalse(i2._deferred)

    def test_ticket_16409(self):
        # Regression for #16409 - make sure defer() and only() work with annotate()
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count("feature")).defer("name")), list
        )
        self.assertIsInstance(
            list(SimpleItem.objects.annotate(Count("feature")).only("name")), list
        )

    def test_ticket_23270(self):
        d = Derived.objects.create(text="foo", other_text="bar")
        with self.assertNumQueries(1):
            obj = Base.objects.select_related("derived").defer("text")[0]
            self.assertIsInstance(obj.derived, Derived)
            self.assertEqual("bar", obj.derived.other_text)
            self.assertNotIn("text", obj.__dict__)
            self.assertEqual(d.pk, obj.derived.base_ptr_id)

    def test_only_and_defer_usage_on_proxy_models(self):
        # Regression for #15790 - only() broken for proxy models
        proxy = Proxy.objects.create(name="proxy", value=42)

        msg = "QuerySet.only() return bogus results with proxy models"
        dp = Proxy.objects.only("other_value").get(pk=proxy.pk)
        self.assertEqual(dp.name, proxy.name, msg=msg)
        self.assertEqual(dp.value, proxy.value, msg=msg)

        # also test things with .defer()
        msg = "QuerySet.defer() return bogus results with proxy models"
        dp = Proxy.objects.defer("name", "text", "value").get(pk=proxy.pk)
        self.assertEqual(dp.name, proxy.name, msg=msg)
        self.assertEqual(dp.value, proxy.value, msg=msg)

    def test_resolve_columns(self):
        ResolveThis.objects.create(num=5.0, name="Foobar")
        qs = ResolveThis.objects.defer("num")
        self.assertEqual(1, qs.count())
        self.assertEqual("Foobar", qs[0].name)

    def test_reverse_one_to_one_relations(self):
        # Refs #14694. Test reverse relations which are known unique (reverse
        # side has o2ofield or unique FK) - the o2o case
        item = Item.objects.create(name="first", value=42)
        o2o = OneToOneItem.objects.create(item=item, name="second")
        self.assertEqual(len(Item.objects.defer("one_to_one_item__name")), 1)
        self.assertEqual(len(Item.objects.select_related("one_to_one_item")), 1)
        self.assertEqual(
            len(
                Item.objects.select_related("one_to_one_item").defer(
                    "one_to_one_item__name"
                )
            ),
            1,
        )
        self.assertEqual(
            len(Item.objects.select_related("one_to_one_item").defer("value")), 1
        )
        # Make sure that `only()` doesn't break when we pass in a unique relation,
        # rather than a field on the relation.
        self.assertEqual(len(Item.objects.only("one_to_one_item")), 1)
        with self.assertNumQueries(1):
            i = Item.objects.select_related("one_to_one_item")[0]
            self.assertEqual(i.one_to_one_item.pk, o2o.pk)
            self.assertEqual(i.one_to_one_item.name, "second")
        with self.assertNumQueries(1):
            i = Item.objects.select_related("one_to_one_item").defer(
                "value", "one_to_one_item__name"
            )[0]
            self.assertEqual(i.one_to_one_item.pk, o2o.pk)
            self.assertEqual(i.name, "first")
        with self.assertNumQueries(1):
            self.assertEqual(i.one_to_one_item.name, "second")
        with self.assertNumQueries(1):
            self.assertEqual(i.value, 42)

    def test_defer_with_select_related(self):
        item1 = Item.objects.create(name="first", value=47)
        item2 = Item.objects.create(name="second", value=42)
        simple = SimpleItem.objects.create(name="simple", value="23")
        ItemAndSimpleItem.objects.create(item=item1, simple=simple)

        obj = ItemAndSimpleItem.objects.defer("item").select_related("simple").get()
        self.assertEqual(obj.item, item1)
        self.assertEqual(obj.item_id, item1.id)

        obj.item = item2
        obj.save()

        obj = ItemAndSimpleItem.objects.defer("item").select_related("simple").get()
        self.assertEqual(obj.item, item2)
        self.assertEqual(obj.item_id, item2.id)

    def test_proxy_model_defer_with_select_related(self):
        # Regression for #22050
        item = Item.objects.create(name="first", value=47)
        RelatedItem.objects.create(item=item)
        # Defer fields with only()
        obj = ProxyRelated.objects.all().select_related().only("item__name")[0]
        with self.assertNumQueries(0):
            self.assertEqual(obj.item.name, "first")
        with self.assertNumQueries(1):
            self.assertEqual(obj.item.value, 47)

    def test_only_with_select_related(self):
        # Test for #17485.
        item = SimpleItem.objects.create(name="first", value=47)
        feature = Feature.objects.create(item=item)
        SpecialFeature.objects.create(feature=feature)

        qs = Feature.objects.only("item__name").select_related("item")
        self.assertEqual(len(qs), 1)

        qs = SpecialFeature.objects.only("feature__item__name").select_related(
            "feature__item"
        )
        self.assertEqual(len(qs), 1)


class DeferAnnotateSelectRelatedTest(TestCase):
    def test_defer_annotate_select_related(self):
        location = Location.objects.create()
        Request.objects.create(location=location)
        self.assertIsInstance(
            list(
                Request.objects.annotate(Count("items"))
                .select_related("profile", "location")
                .only("profile", "location")
            ),
            list,
        )
        self.assertIsInstance(
            list(
                Request.objects.annotate(Count("items"))
                .select_related("profile", "location")
                .only("profile__profile1", "location__location1")
            ),
            list,
        )
        self.assertIsInstance(
            list(
                Request.objects.annotate(Count("items"))
                .select_related("profile", "location")
                .defer("request1", "request2", "request3", "request4")
            ),
            list,
        )


class DeferDeletionSignalsTests(TestCase):
    senders = [Item, Proxy]

    @classmethod
    def setUpTestData(cls):
        cls.item_pk = Item.objects.create(value=1).pk

    def setUp(self):
        self.pre_delete_senders = []
        self.post_delete_senders = []
        for sender in self.senders:
            models.signals.pre_delete.connect(self.pre_delete_receiver, sender)
            models.signals.post_delete.connect(self.post_delete_receiver, sender)

    def tearDown(self):
        for sender in self.senders:
            models.signals.pre_delete.disconnect(self.pre_delete_receiver, sender)
            models.signals.post_delete.disconnect(self.post_delete_receiver, sender)

    def pre_delete_receiver(self, sender, **kwargs):
        self.pre_delete_senders.append(sender)

    def post_delete_receiver(self, sender, **kwargs):
        self.post_delete_senders.append(sender)

    def test_delete_defered_model(self):
        Item.objects.only("value").get(pk=self.item_pk).delete()
        self.assertEqual(self.pre_delete_senders, [Item])
        self.assertEqual(self.post_delete_senders, [Item])

    def test_delete_defered_proxy_model(self):
        Proxy.objects.only("value").get(pk=self.item_pk).delete()
        self.assertEqual(self.pre_delete_senders, [Proxy])
        self.assertEqual(self.post_delete_senders, [Proxy])