django/tests/update_only_fields/tests.py

from django.db.models.signals import post_save, pre_save
from django.test import TestCase

from .models import Account, Employee, Person, Profile, ProxyEmployee


class UpdateOnlyFieldsTests(TestCase):
    msg = (
        "The following fields do not exist in this model, are m2m fields, or "
        "are non-concrete fields: %s"
    )

    def test_update_fields_basic(self):
        s = Person.objects.create(name="Sara", gender="F")
        self.assertEqual(s.gender, "F")

        s.gender = "M"
        s.name = "Ian"
        s.save(update_fields=["name"])

        s = Person.objects.get(pk=s.pk)
        self.assertEqual(s.gender, "F")
        self.assertEqual(s.name, "Ian")

    def test_update_fields_deferred(self):
        s = Person.objects.create(name="Sara", gender="F", pid=22)
        self.assertEqual(s.gender, "F")

        s1 = Person.objects.defer("gender", "pid").get(pk=s.pk)
        s1.name = "Emily"
        s1.gender = "M"

        with self.assertNumQueries(1):
            s1.save()

        s2 = Person.objects.get(pk=s1.pk)
        self.assertEqual(s2.name, "Emily")
        self.assertEqual(s2.gender, "M")

    def test_update_fields_only_1(self):
        s = Person.objects.create(name="Sara", gender="F")
        self.assertEqual(s.gender, "F")

        s1 = Person.objects.only("name").get(pk=s.pk)
        s1.name = "Emily"
        s1.gender = "M"

        with self.assertNumQueries(1):
            s1.save()

        s2 = Person.objects.get(pk=s1.pk)
        self.assertEqual(s2.name, "Emily")
        self.assertEqual(s2.gender, "M")

    def test_update_fields_only_2(self):
        s = Person.objects.create(name="Sara", gender="F", pid=22)
        self.assertEqual(s.gender, "F")

        s1 = Person.objects.only("name").get(pk=s.pk)
        s1.name = "Emily"
        s1.gender = "M"

        with self.assertNumQueries(2):
            s1.save(update_fields=["pid"])

        s2 = Person.objects.get(pk=s1.pk)
        self.assertEqual(s2.name, "Sara")
        self.assertEqual(s2.gender, "F")

    def test_update_fields_only_repeated(self):
        s = Person.objects.create(name="Sara", gender="F")
        self.assertEqual(s.gender, "F")

        s1 = Person.objects.only("name").get(pk=s.pk)
        s1.gender = "M"
        with self.assertNumQueries(1):
            s1.save()
        # save() should not fetch deferred fields
        s1 = Person.objects.only("name").get(pk=s.pk)
        with self.assertNumQueries(1):
            s1.save()

    def test_update_fields_inheritance_defer(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        e1 = Employee.objects.create(
            name="Sara", gender="F", employee_num=1, profile=profile_boss
        )
        e1 = Employee.objects.only("name").get(pk=e1.pk)
        e1.name = "Linda"
        with self.assertNumQueries(1):
            e1.save()
        self.assertEqual(Employee.objects.get(pk=e1.pk).name, "Linda")

    def test_update_fields_fk_defer(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        profile_receptionist = Profile.objects.create(name="Receptionist", salary=1000)
        e1 = Employee.objects.create(
            name="Sara", gender="F", employee_num=1, profile=profile_boss
        )
        e1 = Employee.objects.only("profile").get(pk=e1.pk)
        e1.profile = profile_receptionist
        with self.assertNumQueries(1):
            e1.save()
        self.assertEqual(Employee.objects.get(pk=e1.pk).profile, profile_receptionist)
        e1.profile_id = profile_boss.pk
        with self.assertNumQueries(1):
            e1.save()
        self.assertEqual(Employee.objects.get(pk=e1.pk).profile, profile_boss)

    def test_select_related_only_interaction(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        e1 = Employee.objects.create(
            name="Sara", gender="F", employee_num=1, profile=profile_boss
        )
        e1 = (
            Employee.objects.only("profile__salary")
            .select_related("profile")
            .get(pk=e1.pk)
        )
        profile_boss.name = "Clerk"
        profile_boss.salary = 1000
        profile_boss.save()
        # The loaded salary of 3000 gets saved, the name of 'Clerk' isn't
        # overwritten.
        with self.assertNumQueries(1):
            e1.profile.save()
        reloaded_profile = Profile.objects.get(pk=profile_boss.pk)
        self.assertEqual(reloaded_profile.name, profile_boss.name)
        self.assertEqual(reloaded_profile.salary, 3000)

    def test_update_fields_m2m(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        e1 = Employee.objects.create(
            name="Sara", gender="F", employee_num=1, profile=profile_boss
        )
        a1 = Account.objects.create(num=1)
        a2 = Account.objects.create(num=2)
        e1.accounts.set([a1, a2])

        with self.assertRaisesMessage(ValueError, self.msg % "accounts"):
            e1.save(update_fields=["accounts"])

    def test_update_fields_inheritance(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        profile_receptionist = Profile.objects.create(name="Receptionist", salary=1000)
        e1 = Employee.objects.create(
            name="Sara", gender="F", employee_num=1, profile=profile_boss
        )

        e1.name = "Ian"
        e1.gender = "M"
        e1.save(update_fields=["name"])

        e2 = Employee.objects.get(pk=e1.pk)
        self.assertEqual(e2.name, "Ian")
        self.assertEqual(e2.gender, "F")
        self.assertEqual(e2.profile, profile_boss)

        e2.profile = profile_receptionist
        e2.name = "Sara"
        e2.save(update_fields=["profile"])

        e3 = Employee.objects.get(pk=e1.pk)
        self.assertEqual(e3.name, "Ian")
        self.assertEqual(e3.profile, profile_receptionist)

        with self.assertNumQueries(1):
            e3.profile = profile_boss
            e3.save(update_fields=["profile_id"])

        e4 = Employee.objects.get(pk=e3.pk)
        self.assertEqual(e4.profile, profile_boss)
        self.assertEqual(e4.profile_id, profile_boss.pk)

    def test_update_fields_inheritance_with_proxy_model(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        profile_receptionist = Profile.objects.create(name="Receptionist", salary=1000)
        e1 = ProxyEmployee.objects.create(
            name="Sara", gender="F", employee_num=1, profile=profile_boss
        )

        e1.name = "Ian"
        e1.gender = "M"
        e1.save(update_fields=["name"])

        e2 = ProxyEmployee.objects.get(pk=e1.pk)
        self.assertEqual(e2.name, "Ian")
        self.assertEqual(e2.gender, "F")
        self.assertEqual(e2.profile, profile_boss)

        e2.profile = profile_receptionist
        e2.name = "Sara"
        e2.save(update_fields=["profile"])

        e3 = ProxyEmployee.objects.get(pk=e1.pk)
        self.assertEqual(e3.name, "Ian")
        self.assertEqual(e3.profile, profile_receptionist)

    def test_update_fields_signals(self):
        p = Person.objects.create(name="Sara", gender="F")
        pre_save_data = []

        def pre_save_receiver(**kwargs):
            pre_save_data.append(kwargs["update_fields"])

        pre_save.connect(pre_save_receiver)
        post_save_data = []

        def post_save_receiver(**kwargs):
            post_save_data.append(kwargs["update_fields"])

        post_save.connect(post_save_receiver)
        p.save(update_fields=["name"])
        self.assertEqual(len(pre_save_data), 1)
        self.assertEqual(len(pre_save_data[0]), 1)
        self.assertIn("name", pre_save_data[0])
        self.assertEqual(len(post_save_data), 1)
        self.assertEqual(len(post_save_data[0]), 1)
        self.assertIn("name", post_save_data[0])

        pre_save.disconnect(pre_save_receiver)
        post_save.disconnect(post_save_receiver)

    def test_update_fields_incorrect_params(self):
        s = Person.objects.create(name="Sara", gender="F")

        with self.assertRaisesMessage(ValueError, self.msg % "first_name"):
            s.save(update_fields=["first_name"])

        # "name" is treated as an iterable so the output is something like
        # "n, a, m, e" but the order isn't deterministic.
        with self.assertRaisesMessage(ValueError, self.msg % ""):
            s.save(update_fields="name")

    def test_empty_update_fields(self):
        s = Person.objects.create(name="Sara", gender="F")
        pre_save_data = []

        def pre_save_receiver(**kwargs):
            pre_save_data.append(kwargs["update_fields"])

        pre_save.connect(pre_save_receiver)
        post_save_data = []

        def post_save_receiver(**kwargs):
            post_save_data.append(kwargs["update_fields"])

        post_save.connect(post_save_receiver)
        # Save is skipped.
        with self.assertNumQueries(0):
            s.save(update_fields=[])
        # Signals were skipped, too...
        self.assertEqual(len(pre_save_data), 0)
        self.assertEqual(len(post_save_data), 0)

        pre_save.disconnect(pre_save_receiver)
        post_save.disconnect(post_save_receiver)

    def test_num_queries_inheritance(self):
        s = Employee.objects.create(name="Sara", gender="F")
        s.employee_num = 1
        s.name = "Emily"
        with self.assertNumQueries(1):
            s.save(update_fields=["employee_num"])
        s = Employee.objects.get(pk=s.pk)
        self.assertEqual(s.employee_num, 1)
        self.assertEqual(s.name, "Sara")
        s.employee_num = 2
        s.name = "Emily"
        with self.assertNumQueries(1):
            s.save(update_fields=["name"])
        s = Employee.objects.get(pk=s.pk)
        self.assertEqual(s.name, "Emily")
        self.assertEqual(s.employee_num, 1)
        # A little sanity check that we actually did updates...
        self.assertEqual(Employee.objects.count(), 1)
        self.assertEqual(Person.objects.count(), 1)
        with self.assertNumQueries(2):
            s.save(update_fields=["name", "employee_num"])

    def test_update_non_concrete_field(self):
        profile_boss = Profile.objects.create(name="Boss", salary=3000)
        with self.assertRaisesMessage(ValueError, self.msg % "non_concrete"):
            profile_boss.save(update_fields=["non_concrete"])