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Fixed #20429 -- Added QuerySet.update_or_create 

Thanks tunixman for the suggestion and Loic Bistuer for the review.
This commit is contained in:
Karol Sikora 2013-05-18 13:49:06 +02:00 committed by Tim Graham
parent 66f3d57b79
commit 6272d2f155
6 changed files with 184 additions and 23 deletions
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1
AUTHORS
View File

@ -530,6 +530,7 @@ answer newbie questions, and generally made Django that much better:
Leo Shklovskii
jason.sidabras@gmail.com
Mikołaj Siedlarek <mikolaj.siedlarek@gmail.com>
Karol Sikora <elektrrrus@gmail.com>
Brenton Simpson <http://theillustratedlife.com>
Jozko Skrablin <jozko.skrablin@gmail.com>
Ben Slavin <benjamin.slavin@gmail.com>

3
django/db/models/manager.py
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@ -154,6 +154,9 @@ class Manager(six.with_metaclass(RenameManagerMethods)):
def get_or_create(self, **kwargs):
return self.get_queryset().get_or_create(**kwargs)
def update_or_create(self, **kwargs):
return self.get_queryset().update_or_create(**kwargs)
def create(self, **kwargs):
return self.get_queryset().create(**kwargs)

89
django/db/models/query.py
View File

@ -364,37 +364,84 @@ class QuerySet(object):
return objs
def get_or_create(self, **kwargs):
def get_or_create(self, defaults=None, **kwargs):
"""
Looks up an object with the given kwargs, creating one if necessary.
Returns a tuple of (object, created), where created is a boolean
specifying whether an object was created.
"""
defaults = kwargs.pop('defaults', {})
lookup = kwargs.copy()
for f in self.model._meta.fields:
if f.attname in lookup:
lookup[f.name] = lookup.pop(f.attname)
lookup, params, _ = self._extract_model_params(defaults, **kwargs)
try:
self._for_write = True
return self.get(**lookup), False
except self.model.DoesNotExist:
return self._create_object_from_params(lookup, params)
def update_or_create(self, defaults=None, **kwargs):
"""
Looks up an object with the given kwargs, updating one with defaults
if it exists, otherwise creates a new one.
Returns a tuple (object, created), where created is a boolean
specifying whether an object was created.
"""
lookup, params, filtered_defaults = self._extract_model_params(defaults, **kwargs)
try:
self._for_write = True
obj = self.get(**lookup)
except self.model.DoesNotExist:
obj, created = self._create_object_from_params(lookup, params)
if created:
return obj, created
for k, v in six.iteritems(filtered_defaults):
setattr(obj, k, v)
try:
sid = transaction.savepoint(using=self.db)
obj.save(update_fields=filtered_defaults.keys(), using=self.db)
transaction.savepoint_commit(sid, using=self.db)
return obj, False
except DatabaseError:
transaction.savepoint_rollback(sid, using=self.db)
six.reraise(sys.exc_info())
def _create_object_from_params(self, lookup, params):
"""
Tries to create an object using passed params.
Used by get_or_create and update_or_create
"""
try:
obj = self.model(**params)
sid = transaction.savepoint(using=self.db)
obj.save(force_insert=True, using=self.db)
transaction.savepoint_commit(sid, using=self.db)
return obj, True
except DatabaseError:
transaction.savepoint_rollback(sid, using=self.db)
exc_info = sys.exc_info()
try:
params = dict((k, v) for k, v in kwargs.items() if LOOKUP_SEP not in k)
params.update(defaults)
obj = self.model(**params)
sid = transaction.savepoint(using=self.db)
obj.save(force_insert=True, using=self.db)
transaction.savepoint_commit(sid, using=self.db)
return obj, True
except DatabaseError:
transaction.savepoint_rollback(sid, using=self.db)
exc_info = sys.exc_info()
try:
return self.get(**lookup), False
except self.model.DoesNotExist:
# Re-raise the DatabaseError with its original traceback.
six.reraise(*exc_info)
return self.get(**lookup), False
except self.model.DoesNotExist:
# Re-raise the DatabaseError with its original traceback.
six.reraise(*exc_info)
def _extract_model_params(self, defaults, **kwargs):
"""
Prepares `lookup` (kwargs that are valid model attributes), `params`
(for creating a model instance) and `filtered_defaults` (defaults
that are valid model attributes) based on given kwargs; for use by
get_or_create and update_or_create.
"""
defaults = defaults or {}
filtered_defaults = {}
lookup = kwargs.copy()
for f in self.model._meta.fields:
# Filter out fields that don't belongs to the model.
if f.attname in lookup:
lookup[f.name] = lookup.pop(f.attname)
if f.attname in defaults:
filtered_defaults[f.name] = defaults.pop(f.attname)
params = dict((k, v) for k, v in kwargs.items() if LOOKUP_SEP not in k)
params.update(filtered_defaults)
return lookup, params, filtered_defaults
def _earliest_or_latest(self, field_name=None, direction="-"):
"""

46
docs/ref/models/querysets.txt
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@ -1330,7 +1330,7 @@ prepared to handle the exception if you are using manual primary keys.
get_or_create
~~~~~~~~~~~~~
.. method:: get_or_create(**kwargs)
.. method:: get_or_create(defaults=None, **kwargs)
A convenience method for looking up an object with the given ``kwargs`` (may be
empty if your model has defaults for all fields), creating one if necessary.
@ -1366,7 +1366,6 @@ found, ``get_or_create()`` will instantiate and save a new object, returning a
tuple of the new object and ``True``. The new object will be created roughly
according to this algorithm::
defaults = kwargs.pop('defaults', {})
params = dict([(k, v) for k, v in kwargs.items() if '__' not in k])
params.update(defaults)
obj = self.model(**params)
@ -1447,6 +1446,49 @@ in the HTTP spec.
chapter because it isn't related to that book, but it can't create it either
because ``title`` field should be unique.
update_or_create
~~~~~~~~~~~~~~~~
.. method:: update_or_create(defaults=None, **kwargs)
.. versionadded:: 1.7
A convenience method for updating an object with the given ``kwargs``, creating
a new one if necessary. The ``defaults`` is a dictionary of (field, value)
pairs used to update the object.
Returns a tuple of ``(object, created)``, where ``object`` is the created or
updated object and ``created`` is a boolean specifying whether a new object was
created.
The ``update_or_create`` method tries to fetch an object from database based on
the given ``kwargs``. If a match is found, it updates the fields passed in the
``defaults`` dictionary.
This is meant as a shortcut to boilerplatish code. For example::
try:
obj = Person.objects.get(first_name='John', last_name='Lennon')
for key, value in updated_values.iteritems():
setattr(obj, key, value)
obj.save()
except Person.DoesNotExist:
updated_values.update({'first_name': 'John', 'last_name': 'Lennon'})
obj = Person(**updated_values)
obj.save()
This pattern gets quite unwieldy as the number of fields in a model goes up.
The above example can be rewritten using ``update_or_create()`` like so::
obj, created = Person.objects.update_or_create(
first_name='John', last_name='Lennon', defaults=updated_values)
For detailed description how names passed in ``kwargs`` are resolved see
:meth:`get_or_create`.
As described above in :meth:`get_or_create`, this method is prone to a
race-condition which can result in multiple rows being inserted simultaneously
if uniqueness is not enforced at the database level.
bulk_create
~~~~~~~~~~~

3
docs/releases/1.7.txt
View File

@ -41,6 +41,9 @@ Minor features
* The ``enter`` argument was added to the
:data:`~django.test.signals.setting_changed` signal.
* The :meth:`QuerySet.update_or_create()
<django.db.models.query.QuerySet.update_or_create>` method was added.
Backwards incompatible changes in 1.7
=====================================

65
tests/get_or_create/tests.py
View File

@ -131,3 +131,68 @@ class GetOrCreateThroughManyToMany(TestCase):
Tag.objects.create(text='foo')
a_thing = Thing.objects.create(name='a')
self.assertRaises(IntegrityError, a_thing.tags.get_or_create, text='foo')
class UpdateOrCreateTests(TestCase):
def test_update(self):
Person.objects.create(
first_name='John', last_name='Lennon', birthday=date(1940, 10, 9)
)
p, created = Person.objects.update_or_create(
first_name='John', last_name='Lennon', defaults={
'birthday': date(1940, 10, 10)
}
)
self.assertFalse(created)
self.assertEqual(p.first_name, 'John')
self.assertEqual(p.last_name, 'Lennon')
self.assertEqual(p.birthday, date(1940, 10, 10))
def test_create(self):
p, created = Person.objects.update_or_create(
first_name='John', last_name='Lennon', defaults={
'birthday': date(1940, 10, 10)
}
)
self.assertTrue(created)
self.assertEqual(p.first_name, 'John')
self.assertEqual(p.last_name, 'Lennon')
self.assertEqual(p.birthday, date(1940, 10, 10))
def test_create_twice(self):
params = {
'first_name': 'John',
'last_name': 'Lennon',
'birthday': date(1940, 10, 10),
}
Person.objects.update_or_create(**params)
# If we execute the exact same statement, it won't create a Person.
p, created = Person.objects.update_or_create(**params)
self.assertFalse(created)
def test_integrity(self):
# If you don't specify a value or default value for all required
# fields, you will get an error.
self.assertRaises(IntegrityError,
Person.objects.update_or_create, first_name="Tom", last_name="Smith")
def test_mananual_primary_key_test(self):
# If you specify an existing primary key, but different other fields,
# then you will get an error and data will not be updated.
ManualPrimaryKeyTest.objects.create(id=1, data="Original")
self.assertRaises(IntegrityError,
ManualPrimaryKeyTest.objects.update_or_create, id=1, data="Different"
)
self.assertEqual(ManualPrimaryKeyTest.objects.get(id=1).data, "Original")
def test_error_contains_full_traceback(self):
# update_or_create should raise IntegrityErrors with the full traceback.
# This is tested by checking that a known method call is in the traceback.
# We cannot use assertRaises/assertRaises here because we need to inspect
# the actual traceback. Refs #16340.
try:
ManualPrimaryKeyTest.objects.update_or_create(id=1, data="Different")
except IntegrityError as e:
formatted_traceback = traceback.format_exc()
self.assertIn('obj.save', formatted_traceback)