Fixed #18306 -- Made deferred models issue update_fields on save

Deferred models now automatically update only the fields which are
loaded from the db (with .only() or .defer()). In addition, any field
set manually after the load is updated on save.

3 files changed, 117 insertions, 0 deletions

diff --git a/tests/modeltests/update_only_fields/models.py b/tests/modeltests/update_only_fields/models.py
index 01184f715b..bf5dd99166 100644
--- a/tests/modeltests/update_only_fields/models.py
+++ b/tests/modeltests/update_only_fields/models.py
@@ -15,6 +15,7 @@ class Account(models.Model):
 class Person(models.Model):
     name = models.CharField(max_length=20)
     gender = models.CharField(max_length=1, choices=GENDER_CHOICES)
+    pid = models.IntegerField(null=True, default=None)
 
     def __str__(self):
         return self.name
diff --git a/tests/modeltests/update_only_fields/tests.py b/tests/modeltests/update_only_fields/tests.py
index bce53ca621..c904c97236 100644
--- a/tests/modeltests/update_only_fields/tests.py
+++ b/tests/modeltests/update_only_fields/tests.py
@@ -18,6 +18,107 @@ class UpdateOnlyFieldsTests(TestCase):
         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()
+        # Test that the deferred class does not remember that gender was
+        # set, instead the instace should remember this.
+        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',
diff --git a/tests/regressiontests/multiple_database/tests.py b/tests/regressiontests/multiple_database/tests.py
index 74a5f2f550..782fe2bfc6 100644
--- a/tests/regressiontests/multiple_database/tests.py
+++ b/tests/regressiontests/multiple_database/tests.py
@@ -1546,6 +1546,21 @@ class RouterTestCase(TestCase):
         # If you evaluate the query, it should work, running on 'other'
         self.assertEqual(list(qs.values_list('title', flat=True)), ['Dive into Python'])
 
+    def test_deferred_models(self):
+        mark_def = Person.objects.using('default').create(name="Mark Pilgrim")
+        mark_other = Person.objects.using('other').create(name="Mark Pilgrim")
+        orig_b = Book.objects.using('other').create(title="Dive into Python",
+                                                    published=datetime.date(2009, 5, 4),
+                                                    editor=mark_other)
+        b = Book.objects.using('other').only('title').get(pk=orig_b.pk)
+        self.assertEqual(b.published, datetime.date(2009, 5, 4))
+        b = Book.objects.using('other').only('title').get(pk=orig_b.pk)
+        b.editor = mark_def
+        b.save(using='default')
+        self.assertEqual(Book.objects.using('default').get(pk=b.pk).published,
+                         datetime.date(2009, 5, 4))
+
+
 class AuthTestCase(TestCase):
     multi_db = True