Ticket #4102: 4102-dirty-set.5.patch

File 4102-dirty-set.5.patch, 5.0 KB (added by SmileyChris, 8 years ago)

Cleaner implementation: doesn't mess with init

  • django/db/models/base.py

     
    1919import sys
    2020import os
    2121
     22try:
     23    set
     24except NameError:
     25    from sets import Set as set   # Python 2.3 fallback
     26
    2227class ModelBase(type):
    2328    "Metaclass for all models"
    2429    def __new__(cls, name, bases, attrs):
     
    97102    def __ne__(self, other):
    98103        return not self.__eq__(other)
    99104
     105    def __setattr__(self, name, value):
     106        if name != '_modified_attrs' and (not hasattr(self, name) or
     107                                          value != getattr(self, name)):
     108            if hasattr(self, '_modified_attrs'):
     109                if value not in self._modified_attrs:
     110                    self._modified_attrs.add(name)
     111            else:
     112                self._modified_attrs = set((value,))
     113        super(Model, self).__setattr__(name, value)
     114
     115    def _reset_modified_attrs(self):
     116        try:
     117            del self._modified_attrs
     118        except KeyError:
     119            pass
     120
    100121    def __init__(self, *args, **kwargs):
    101122        dispatcher.send(signal=signals.pre_init, sender=self.__class__, args=args, kwargs=kwargs)
    102123
    103124        # There is a rather weird disparity here; if kwargs, it's set, then args
    104         # overrides it. It should be one or the other; don't duplicate the work
     125        # overrides it. It should be one or the other; don't duplicate the work.
    105126        # The reason for the kwargs check is that standard iterator passes in by
    106         # args, and nstantiation for iteration is 33% faster.
     127        # args, and instantiation for iteration is 33% faster.
    107128        args_len = len(args)
    108129        if args_len > len(self._meta.fields):
    109130            # Daft, but matches old exception sans the err msg.
     
    202223    _prepare = classmethod(_prepare)
    203224
    204225    def save(self, raw=False):
     226        "Save model object to database, creating if doesn't exist, otherwise updating"
    205227        dispatcher.send(signal=signals.pre_save, sender=self.__class__, instance=self)
    206228
    207229        non_pks = [f for f in self._meta.fields if not f.primary_key]
     230        if hasattr(self, '_modified_attrs'):
     231            ma = self._modified_attrs
     232            non_pks = [f for f in non_pks if (f.name in ma or f.attname in ma)]
     233            self._reset_modified_attrs()
    208234        cursor = connection.cursor()
    209235
    210236        # First, try an UPDATE. If that doesn't update anything, do an INSERT.
  • django/db/models/query.py

     
    203203                                                    index_start=0, max_depth=self._max_related_depth)
    204204                else:
    205205                    obj = self.model(*row[:index_end])
     206                    # Models keep a track of modified attrs to choose which
     207                    # fields to save. Since we're just pulling from the
     208                    # database, nothing has changed yet.
     209                    obj._reset_modified_attrs()
    206210                for i, k in enumerate(extra_select):
    207211                    setattr(obj, k[0], row[index_end+i])
    208212                yield obj
  • tests/modeltests/update_fields/models.py

     
     1"""
     2#. Save only modified fields on update
     3"""
     4from django.db import models
     5
     6class Article(models.Model):
     7    headline = models.CharField(maxlength=100, default='Default headline')
     8    body = models.TextField()
     9    pub_date = models.DateTimeField()
     10
     11    class Meta:
     12        ordering = ('pub_date','headline')
     13
     14    def __str__(self):
     15        return self.headline
     16
     17__test__ = {'API_TESTS':"""
     18# Create a couple of Articles.
     19>>> from datetime import datetime
     20>>> a = Article(headline='Article 1', body='Body 1', pub_date=datetime(2007, 5, 5))
     21>>> a.save()
     22
     23# Change headline and body on different instances, then save both to verify
     24# that each only updated the modified field.
     25>>> a1 = Article.objects.get(pk=a.id)
     26>>> a2 = Article.objects.get(pk=a.id)
     27>>> a1.headline = 'Changed article 1'
     28>>> a2.body = 'Changed body 1'
     29>>> a1.save()
     30>>> a2.save()
     31>>> a3 = Article.objects.get(pk=a.id)
     32>>> a3.headline
     33u'Changed article 1'
     34>>> a3.body
     35u'Changed body 1'
     36
     37# Fields entered at istantiation of a model which will already exists should be
     38# saved as well.
     39>>> a = Article(id=a.id, headline='Reset article 1', body='Reset body 1', pub_date=datetime(2007, 5, 5))
     40>>> a.save()
     41>>> a3 = Article.objects.get(pk=a.id)
     42>>> a3.headline
     43u'Reset article 1'
     44>>> a3.body
     45u'Reset body 1'
     46"""}
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