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-rw-r--r--django/db/models/base.py18
-rw-r--r--docs/ref/models/instances.txt6
-rw-r--r--docs/ref/models/querysets.txt16
-rw-r--r--docs/releases/1.5.txt4
-rw-r--r--tests/modeltests/update_only_fields/models.py1
-rw-r--r--tests/modeltests/update_only_fields/tests.py101
-rw-r--r--tests/regressiontests/multiple_database/tests.py15
7 files changed, 161 insertions, 0 deletions
diff --git a/django/db/models/base.py b/django/db/models/base.py
index 30e07be3a7..1e1a138714 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -475,6 +475,7 @@ class Model(six.with_metaclass(ModelBase, object)):
that the "save" must be an SQL insert or update (or equivalent for
non-SQL backends), respectively. Normally, they should not be set.
"""
+ using = using or router.db_for_write(self.__class__, instance=self)
if force_insert and (force_update or update_fields):
raise ValueError("Cannot force both insert and updating in model saving.")
@@ -502,6 +503,23 @@ class Model(six.with_metaclass(ModelBase, object)):
"model or are m2m fields: %s"
% ', '.join(non_model_fields))
+ # If saving to the same database, and this model is deferred, then
+ # automatically do a "update_fields" save on the loaded fields.
+ elif not force_insert and self._deferred and using == self._state.db:
+ field_names = set()
+ for field in self._meta.fields:
+ if not field.primary_key and not hasattr(field, 'through'):
+ field_names.add(field.attname)
+ deferred_fields = [
+ f.attname for f in self._meta.fields
+ if f.attname not in self.__dict__
+ and isinstance(self.__class__.__dict__[f.attname],
+ DeferredAttribute)]
+
+ loaded_fields = field_names.difference(deferred_fields)
+ if loaded_fields:
+ update_fields = frozenset(loaded_fields)
+
self.save_base(using=using, force_insert=force_insert,
force_update=force_update, update_fields=update_fields)
save.alters_data = True
diff --git a/docs/ref/models/instances.txt b/docs/ref/models/instances.txt
index 14541ad0d1..b7ae3890cf 100644
--- a/docs/ref/models/instances.txt
+++ b/docs/ref/models/instances.txt
@@ -386,6 +386,12 @@ perform an update on all fields.
Specifying ``update_fields`` will force an update.
+When saving a model fetched through deferred model loading
+(:meth:`~Model.only()` or :meth:`~Model.defer()`) only the fields loaded from
+the DB will get updated. In effect there is an automatic ``update_fields`` in
+this case. If you assign or change any deferred field value, these fields will
+be added to the updated fields.
+
Deleting objects
================
diff --git a/docs/ref/models/querysets.txt b/docs/ref/models/querysets.txt
index 8c188c67c3..b59b2ece82 100644
--- a/docs/ref/models/querysets.txt
+++ b/docs/ref/models/querysets.txt
@@ -1110,6 +1110,14 @@ one, doing so will result in an error.
reader, is slightly faster and consumes a little less memory in the Python
process.
+.. versionchanged:: 1.5
+
+.. note::
+
+ When calling :meth:`~Model.save()` for instances with deferred fields,
+ only the loaded fields will be saved. See :meth:`~Model.save()` for more
+ details.
+
only
~~~~
@@ -1154,6 +1162,14 @@ All of the cautions in the note for the :meth:`defer` documentation apply to
options. Also note that using :meth:`only` and omitting a field requested
using :meth:`select_related` is an error as well.
+.. versionchanged:: 1.5
+
+.. note::
+
+ When calling :meth:`~Model.save()` for instances with deferred fields,
+ only the loaded fields will be saved. See :meth:`~Model.save()` for more
+ details.
+
using
~~~~~
diff --git a/docs/releases/1.5.txt b/docs/releases/1.5.txt
index 4aeb61af94..2896acb36b 100644
--- a/docs/releases/1.5.txt
+++ b/docs/releases/1.5.txt
@@ -42,6 +42,10 @@ keyword argument ``update_fields``. By using this argument it is possible to
save only a select list of model's fields. This can be useful for performance
reasons or when trying to avoid overwriting concurrent changes.
+Deferred instances (those loaded by .only() or .defer()) will automatically
+save just the loaded fields. If any field is set manually after load, that
+field will also get updated on save.
+
See the :meth:`Model.save() <django.db.models.Model.save()>` documentation for
more details.
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
generated by cgit v1.3 (git 2.53.0) at 2026-07-08 14:11:36 +0000