Ticket #4102: only_fields_django-1.4.patch

File only_fields_django-1.4.patch, 4.5 KB (added by niwi, 3 years ago)
  • docs/ref/models/instances.txt

     
    135135
    136136To save an object back to the database, call ``save()``:
    137137
    138 .. method:: Model.save([force_insert=False, force_update=False, using=DEFAULT_DB_ALIAS])
     138.. method:: Model.save([force_insert=False, force_update=False, using=DEFAULT_DB_ALIAS, only_fields=None])
    139139
    140140.. versionadded:: 1.2
    141141   The ``using`` argument was added.
     
    334334<query-expressions>` and their :ref:`use in update queries
    335335<topics-db-queries-update>`.
    336336
     337Specifying which fields to save
     338-------------------------------
     339
     340If ``save()`` is passed a list of field names as keyword argument ``only_fields``,
     341only the fields named in that list will be saved to the database. This may be
     342desirable if you want to update just one or a few fields on an object, as there
     343will be a slight performance benefit from preventing all of the model fields
     344from being updated in the database. For example:
     345
     346    product.name = 'Name changed again'
     347    product.save(only_fields=['name'])
     348
     349
    337350Deleting objects
    338351================
    339352
  • django/db/models/base.py

     
    449449            return getattr(self, field_name)
    450450        return getattr(self, field.attname)
    451451
    452     def save(self, force_insert=False, force_update=False, using=None):
     452    def save(self, force_insert=False, force_update=False, using=None, only_fields=None):
    453453        """
    454454        Saves the current instance. Override this in a subclass if you want to
    455455        control the saving process.
     
    460460        """
    461461        if force_insert and force_update:
    462462            raise ValueError("Cannot force both insert and updating in model saving.")
    463         self.save_base(using=using, force_insert=force_insert, force_update=force_update)
     463        self.save_base(using=using, force_insert=force_insert,
     464                        force_update=force_update, only_fields=only_fields)
    464465
    465466    save.alters_data = True
    466467
    467468    def save_base(self, raw=False, cls=None, origin=None, force_insert=False,
    468             force_update=False, using=None):
     469            force_update=False, using=None, only_fields=None):
    469470        """
    470471        Does the heavy-lifting involved in saving. Subclasses shouldn't need to
    471472        override this method. It's separate from save() in order to hide the
     
    513514        if not meta.proxy:
    514515            non_pks = [f for f in meta.local_fields if not f.primary_key]
    515516
     517            if only_fields:
     518                non_pks = [f for f in non_pks if f.name in only_fields]
     519
    516520            # First, try an UPDATE. If that doesn't update anything, do an INSERT.
    517521            pk_val = self._get_pk_val(meta)
    518522            pk_set = pk_val is not None
  • tests/modeltests/update_only_fields/__init__.py

     
     1# -*- coding: utf-8 -*-
     2
     3
  • tests/modeltests/update_only_fields/tests.py

     
     1from __future__ import absolute_import
     2
     3from django.test import TestCase
     4from .models import Person
     5
     6class UpdateOnlyFieldsTests(TestCase):
     7    def test_only_update(self):
     8        s = Person.objects.create(name='Sara', gender='F')
     9        self.assertEqual(s.gender, 'F')
     10
     11        s.gender = 'M'
     12        s.save(only_fields=['name'])
     13
     14        s = Person.objects.get(pk=s.pk)
     15        self.assertEqual(s.gender, 'F')
  • tests/modeltests/update_only_fields/models.py

     
     1
     2from django.db import models
     3
     4GENDER_CHOICES = (
     5    ('M', 'Male'),
     6    ('F', 'Female'),
     7)
     8
     9class Person(models.Model):
     10    name = models.CharField(max_length=20)
     11    gender = models.CharField(max_length=1, choices=GENDER_CHOICES)
     12
     13    def __unicode__(self):
     14        return self.name
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