Ticket #7539: 7539.on_delete.r11706.diff

File 7539.on_delete.r11706.diff, 26.3 KB (added by Johannes Dollinger, 14 years ago)

  • tests/modeltests/on_delete/tests.py

     
     1from django.test import TestCase
     2from django.db import models, IntegrityError
     3
     4class R(models.Model):
     5    is_default = models.BooleanField(default=False)
     6
     7    def __str__(self):
     8        return "%s" % self.pk
     9
     10get_default_r = lambda: R.objects.get_or_create(is_default=True)[0]
     11   
     12class S(models.Model):
     13    r = models.ForeignKey(R)
     14   
     15class T(models.Model):
     16    s = models.ForeignKey(S)
     17
     18class A(models.Model):
     19    name = models.CharField(max_length=10)   
     20
     21    auto = models.ForeignKey(R, related_name="auto_set")
     22    auto_nullable = models.ForeignKey(R, null=True, related_name='auto_nullable_set')
     23    setnull = models.ForeignKey(R, on_delete=models.SET_NULL, null=True, related_name='setnull_set')
     24    setdefault = models.ForeignKey(R, on_delete=models.SET_DEFAULT, default=get_default_r, related_name='setdefault_set')
     25    setdefault_none = models.ForeignKey(R, on_delete=models.SET_DEFAULT, default=None, null=True, related_name='setnull_nullable_set')
     26    cascade = models.ForeignKey(R, on_delete=models.CASCADE, related_name='cascade_set')
     27    cascade_nullable = models.ForeignKey(R, on_delete=models.CASCADE, null=True, related_name='cascade_nullable_set')
     28    protect = models.ForeignKey(R, on_delete=models.PROTECT, null=True)
     29    donothing = models.ForeignKey(R, on_delete=models.DO_NOTHING, null=True, related_name='donothing_set')
     30   
     31def create_a(name):
     32    a = A(name=name)
     33    for name in ('auto', 'auto_nullable', 'setnull', 'setdefault', 'setdefault_none', 'cascade', 'cascade_nullable', 'protect', 'donothing'):
     34        r = R.objects.create()
     35        setattr(a, name, r)
     36    a.save()
     37    return a
     38
     39class OnDeleteTests(TestCase):
     40    def test_basics(self):
     41        DEFAULT = get_default_r()
     42       
     43        a = create_a('auto')
     44        a.auto.delete()
     45        self.failIf(A.objects.filter(name='auto').exists())
     46       
     47        a = create_a('auto_nullable')
     48        a.auto_nullable.delete()
     49        self.failUnlessEqual([a], list(A.objects.all()))
     50       
     51        a = create_a('setnull')
     52        a.setnull.delete()
     53        a = A.objects.get(pk=a.pk)
     54        self.failUnlessEqual(None, a.setnull)
     55       
     56        a = create_a('setdefault')
     57        a.setdefault.delete()
     58        a = A.objects.get(pk=a.pk)
     59        self.failUnlessEqual(DEFAULT, a.setdefault)
     60       
     61        a = create_a('setdefault_none')
     62        a.setdefault_none.delete()
     63        a = A.objects.get(pk=a.pk)
     64        self.failUnlessEqual(None, a.setdefault_none)
     65       
     66        a = create_a('cascade')
     67        a.cascade.delete()
     68        self.failIf(A.objects.filter(name='cascade').exists())
     69       
     70        a = create_a('cascade_nullable')
     71        a.cascade_nullable.delete()
     72        self.failIf(A.objects.filter(name='cascade_nullable').exists())
     73       
     74        a = create_a('protect')
     75        self.assertRaises(IntegrityError, a.protect.delete)
     76       
     77        # Testing DO_NOTHING is a bit harder: It would raise IntegrityError for a normal model,
     78        # so we connect to pre_delete and set the fk to a known value.
     79        replacement_r = R.objects.create()
     80        def check_do_nothing(sender, **kwargs):
     81            obj = kwargs['instance']
     82            obj.donothing_set.update(donothing=replacement_r)
     83        models.signals.pre_delete.connect(check_do_nothing)
     84        a = create_a('do_nothing')
     85        a.donothing.delete()
     86        a = A.objects.get(pk=a.pk)
     87        self.failUnlessEqual(replacement_r, a.donothing)
     88        models.signals.pre_delete.disconnect(check_do_nothing)       
     89       
     90        # cleanup
     91        A.objects.all().update(protect=None, donothing=None)
     92        R.objects.all().delete()
     93        self.failIf(A.objects.exists())
     94       
     95    def test_cache_update(self):
     96        deleted = []
     97        related_setnull_sets = []
     98        def pre_delete(sender, **kwargs):
     99            obj = kwargs['instance']
     100            deleted.append(obj)
     101            if isinstance(obj, R):
     102                related_setnull_sets.append(list(a.pk for a in obj.setnull_set.all()))
     103
     104        models.signals.pre_delete.connect(pre_delete)
     105        a = create_a('cache_update_setnull')
     106        a.setnull.delete()
     107       
     108        a = create_a('cache_update_setnull')
     109        a.cascade.delete()
     110       
     111        for obj in deleted:
     112            self.failUnlessEqual(None, obj.pk)
     113           
     114        for pk_list in related_setnull_sets:
     115            for a in A.objects.filter(id__in=pk_list):
     116                self.failUnlessEqual(None, a.setnull)
     117       
     118        models.signals.pre_delete.disconnect(pre_delete)
     119
     120    def test_deletion_order(self):
     121        pre_delete_order = []
     122        post_delete_order = []
     123
     124        def log_post_delete(sender, **kwargs):
     125            pre_delete_order.append((sender, kwargs['instance'].pk))
     126
     127        def log_pre_delete(sender, **kwargs):
     128            post_delete_order.append((sender, kwargs['instance'].pk))
     129       
     130        models.signals.post_delete.connect(log_post_delete)
     131        models.signals.pre_delete.connect(log_pre_delete)
     132       
     133        r = R.objects.create(pk=1)
     134        s1 = S.objects.create(pk=1, r=r)
     135        s2 = S.objects.create(pk=2, r=r)
     136        t1 = T.objects.create(pk=1, s=s1)
     137        t2 = T.objects.create(pk=2, s=s2)
     138        r.delete()
     139        self.failUnlessEqual(pre_delete_order, [(T, 2), (T, 1), (S, 2), (S, 1), (R, 1)])
     140        self.failUnlessEqual(post_delete_order, [(T, 1), (T, 2), (S, 1), (S, 2), (R, 1)])
     141       
     142        models.signals.post_delete.disconnect(log_post_delete)
     143        models.signals.post_delete.disconnect(log_pre_delete)
     144       

  • tests/modeltests/delete/models.py

     
    4444__test__ = {'API_TESTS': """
    4545### Tests for models A,B,C,D ###
    4646
    47 ## First, test the CollectedObjects data structure directly
    48 
    49 >>> from django.db.models.query import CollectedObjects
    50 
    51 >>> g = CollectedObjects()
    52 >>> g.add("key1", 1, "item1", None)
    53 False
    54 >>> g["key1"]
    55 {1: 'item1'}
    56 >>> g.add("key2", 1, "item1", "key1")
    57 False
    58 >>> g.add("key2", 2, "item2", "key1")
    59 False
    60 >>> g["key2"]
    61 {1: 'item1', 2: 'item2'}
    62 >>> g.add("key3", 1, "item1", "key1")
    63 False
    64 >>> g.add("key3", 1, "item1", "key2")
    65 True
    66 >>> g.ordered_keys()
    67 ['key3', 'key2', 'key1']
    68 
    69 >>> g.add("key2", 1, "item1", "key3")
    70 True
    71 >>> g.ordered_keys()
    72 Traceback (most recent call last):
    73     ...
    74 CyclicDependency: There is a cyclic dependency of items to be processed.
    75 
    76 
    77 ## Second, test the usage of CollectedObjects by Model.delete()
    78 
    7947# Due to the way that transactions work in the test harness,
    8048# doing m.delete() here can work but fail in a real situation,
    8149# since it may delete all objects, but not in the right order.
    … …  
    11179>>> c1.save()
    11280>>> d1 = D(c=c1, a=a1)
    11381>>> d1.save()
    114 
    115 >>> o = CollectedObjects()
    116 >>> a1._collect_sub_objects(o)
    117 >>> o.keys()
    118 [<class 'modeltests.delete.models.D'>, <class 'modeltests.delete.models.C'>, <class 'modeltests.delete.models.B'>, <class 'modeltests.delete.models.A'>]
    11982>>> a1.delete()
    12083
    12184# Same again with a known bad order
    … …  
    13093>>> c2.save()
    13194>>> d2 = D(c=c2, a=a2)
    13295>>> d2.save()
    133 
    134 >>> o = CollectedObjects()
    135 >>> a2._collect_sub_objects(o)
    136 >>> o.keys()
    137 [<class 'modeltests.delete.models.D'>, <class 'modeltests.delete.models.C'>, <class 'modeltests.delete.models.B'>, <class 'modeltests.delete.models.A'>]
    13896>>> a2.delete()
    13997
    14098### Tests for models E,F - nullable related fields ###
    14199
    142 ## First, test the CollectedObjects data structure directly
    143 
    144 >>> g = CollectedObjects()
    145 >>> g.add("key1", 1, "item1", None)
    146 False
    147 >>> g.add("key2", 1, "item1", "key1", nullable=True)
    148 False
    149 >>> g.add("key1", 1, "item1", "key2")
    150 True
    151 >>> g.ordered_keys()
    152 ['key1', 'key2']
    153 
    154 ## Second, test the usage of CollectedObjects by Model.delete()
    155 
    156100>>> e1 = E()
    157101>>> e1.save()
    158102>>> f1 = F(e=e1)
    159103>>> f1.save()
    160104>>> e1.f = f1
    161105>>> e1.save()
    162 
    163 # Since E.f is nullable, we should delete F first (after nulling out
    164 # the E.f field), then E.
    165 
    166 >>> o = CollectedObjects()
    167 >>> e1._collect_sub_objects(o)
    168 >>> o.keys()
    169 [<class 'modeltests.delete.models.F'>, <class 'modeltests.delete.models.E'>]
    170 
    171 # temporarily replace the UpdateQuery class to verify that E.f is actually nulled out first
    172 >>> import django.db.models.sql
    173 >>> class LoggingUpdateQuery(django.db.models.sql.UpdateQuery):
    174 ...     def clear_related(self, related_field, pk_list):
    175 ...         print "CLEARING FIELD",related_field.name
    176 ...         return super(LoggingUpdateQuery, self).clear_related(related_field, pk_list)
    177 >>> original_class = django.db.models.sql.UpdateQuery
    178 >>> django.db.models.sql.UpdateQuery = LoggingUpdateQuery
    179106>>> e1.delete()
    180 CLEARING FIELD f
    181107
    182108>>> e2 = E()
    183109>>> e2.save()
    … …  
    185111>>> f2.save()
    186112>>> e2.f = f2
    187113>>> e2.save()
    188 
    189 # Same deal as before, though we are starting from the other object.
    190 
    191 >>> o = CollectedObjects()
    192 >>> f2._collect_sub_objects(o)
    193 >>> o.keys()
    194 [<class 'modeltests.delete.models.F'>, <class 'modeltests.delete.models.E'>]
    195 
    196114>>> f2.delete()
    197 CLEARING FIELD f
    198 
    199 # Put this back to normal
    200 >>> django.db.models.sql.UpdateQuery = original_class
    201115"""
    202116}

  • django/db/models/base.py

     
    523523             (model_class, {pk_val: obj, pk_val: obj, ...}), ...]
    524524        """
    525525        pk_val = self._get_pk_val()
    526         if seen_objs.add(self.__class__, pk_val, self, parent, nullable):
     526        if seen_objs.add(self, parent, nullable):
    527527            return
    528528
    529529        for related in self._meta.get_all_related_objects():
    … …  
    534534                except ObjectDoesNotExist:
    535535                    pass
    536536                else:
    537                     sub_obj._collect_sub_objects(seen_objs, self.__class__, related.field.null)
     537                    related.field.rel.on_delete(self, related, sub_obj, seen_objs)
    538538            else:
    539539                # To make sure we can access all elements, we can't use the
    540540                # normal manager on the related object. So we work directly
    … …  
    547547                    raise AssertionError("Should never get here.")
    548548                delete_qs = rel_descriptor.delete_manager(self).all()
    549549                for sub_obj in delete_qs:
    550                     sub_obj._collect_sub_objects(seen_objs, self.__class__, related.field.null)
     550                    related.field.rel.on_delete(self, related, sub_obj, seen_objs)
    551551
    552552        # Handle any ancestors (for the model-inheritance case). We do this by
    553553        # traversing to the most remote parent classes -- those with no parents

  • django/db/models/fields/related.py

     
    1 from django.db import connection, transaction
     1from django.db import connection, transaction, IntegrityError
    22from django.db.backends import util
    33from django.db.models import signals, get_model
    44from django.db.models.fields import AutoField, Field, IntegerField, PositiveIntegerField, PositiveSmallIntegerField, FieldDoesNotExist
    … …  
    1818
    1919RECURSIVE_RELATIONSHIP_CONSTANT = 'self'
    2020
     21def CASCADE(obj, related, sub_obj, seen_objs):
     22    sub_obj._collect_sub_objects(seen_objs, obj.__class__)
     23
     24def PROTECT(obj, related, sub_obj, seen_objs):
     25    msg = '[Django] Cannot delete a parent object: a foreign key constraint fails (ForeignKey `%s` (pk=`%s`) references `%s` (pk=`%s`))' % (
     26        sub_obj.__class__, sub_obj.pk,
     27        obj.__class__, obj.pk,
     28    )
     29    raise IntegrityError(msg)
     30
     31def SET(value):
     32    def set_on_delete(obj, related, sub_obj, seen_objs):
     33        seen_objs.add(sub_obj, related.field, value)
     34    return set_on_delete
     35
     36def SET_NULL(obj, related, sub_obj, seen_objs):
     37    seen_objs.add_field_update(sub_obj, related.field, None)
     38
     39def SET_DEFAULT(obj, related, sub_obj, seen_objs):
     40    seen_objs.add_field_update(sub_obj, related.field, related.field.get_default())
     41
     42def DO_NOTHING(obj, related, sub_obj, seen_objs):
     43    pass
     44
     45
    2146pending_lookups = {}
    2247
    2348def add_lazy_relation(cls, field, relation, operation):
    … …  
    628653
    629654class ManyToOneRel(object):
    630655    def __init__(self, to, field_name, related_name=None,
    631             limit_choices_to=None, lookup_overrides=None, parent_link=False):
     656            limit_choices_to=None, lookup_overrides=None, parent_link=False,
     657            on_delete=None):
    632658        try:
    633659            to._meta
    634660        except AttributeError: # to._meta doesn't exist, so it must be RECURSIVE_RELATIONSHIP_CONSTANT
    … …  
    641667        self.lookup_overrides = lookup_overrides or {}
    642668        self.multiple = True
    643669        self.parent_link = parent_link
     670        self.on_delete = on_delete
    644671
    645672    def get_related_field(self):
    646673        """
    … …  
    655682
    656683class OneToOneRel(ManyToOneRel):
    657684    def __init__(self, to, field_name, related_name=None,
    658             limit_choices_to=None, lookup_overrides=None, parent_link=False):
     685            limit_choices_to=None, lookup_overrides=None, parent_link=False,
     686            on_delete=None):
    659687        super(OneToOneRel, self).__init__(to, field_name,
    660688                related_name=related_name, limit_choices_to=limit_choices_to,
    661                 lookup_overrides=lookup_overrides, parent_link=parent_link)
     689                lookup_overrides=lookup_overrides, parent_link=parent_link,
     690                on_delete=on_delete)
    662691        self.multiple = False
    663692
    664693class ManyToManyRel(object):
    … …  
    692721            assert not to._meta.abstract, "%s cannot define a relation with abstract class %s" % (self.__class__.__name__, to._meta.object_name)
    693722            to_field = to_field or to._meta.pk.name
    694723        kwargs['verbose_name'] = kwargs.get('verbose_name', None)
     724       
     725        on_delete = kwargs.pop('on_delete', None)
     726        if on_delete is None:
     727            if kwargs.get('null', False):
     728                on_delete = SET_NULL
     729            else:
     730                on_delete = CASCADE
    695731
    696732        kwargs['rel'] = rel_class(to, to_field,
    697733            related_name=kwargs.pop('related_name', None),
    698734            limit_choices_to=kwargs.pop('limit_choices_to', None),
    699735            lookup_overrides=kwargs.pop('lookup_overrides', None),
    700             parent_link=kwargs.pop('parent_link', False))
     736            parent_link=kwargs.pop('parent_link', False),
     737            on_delete=on_delete)
    701738        Field.__init__(self, **kwargs)
    702739
    703740        self.db_index = True
    … …  
    742779            target = self.rel.to._meta.db_table
    743780        cls._meta.duplicate_targets[self.column] = (target, "o2m")
    744781
     782        on_delete = self.rel.on_delete
     783        if on_delete == SET_NULL and not self.null:
     784            specification = "'on_delete=SET_NULL'"
     785            raise ValueError("%s specified for %s '%s.%s', but the field is not nullable." % (specification, type(self).__name__, cls.__name__, name))
     786        if on_delete == SET_DEFAULT and not self.has_default():
     787            specification = "'on_delete=SET_DEFAULT'"
     788            raise ValueError("%s specified for %s '%s.%s', but the field has no default value." % (specification, type(self).__name__, cls.__name__, name))
     789
    745790    def contribute_to_related_class(self, cls, related):
    746791        setattr(cls, related.get_accessor_name(), ForeignRelatedObjectsDescriptor(related))
    747792

  • django/db/models/__init__.py

     
    1111from django.db.models.fields.subclassing import SubfieldBase
    1212from django.db.models.fields.files import FileField, ImageField
    1313from django.db.models.fields.related import ForeignKey, OneToOneField, ManyToManyField, ManyToOneRel, ManyToManyRel, OneToOneRel
     14from django.db.models.fields.related import CASCADE, PROTECT, SET, SET_NULL, SET_DEFAULT, DO_NOTHING
    1415from django.db.models import signals
    1516
    1617# Admin stages.

  • django/db/models/query.py

     
    10111011    else:
    10121012        forced_managed = False
    10131013    try:
    1014         ordered_classes = seen_objs.keys()
    1015     except CyclicDependency:
    1016         # If there is a cyclic dependency, we cannot in general delete the
    1017         # objects.  However, if an appropriate transaction is set up, or if the
    1018         # database is lax enough, it will succeed. So for now, we go ahead and
    1019         # try anyway.
    1020         ordered_classes = seen_objs.unordered_keys()
     1014        try:
     1015            seen_objs.sort()
     1016        except CyclicDependency:
     1017            pass
    10211018
    1022     obj_pairs = {}
    1023     try:
    1024         for cls in ordered_classes:
    1025             items = seen_objs[cls].items()
    1026             items.sort()
    1027             obj_pairs[cls] = items
     1019        for obj in seen_objs:
     1020            signals.pre_delete.send(sender=obj.__class__, instance=obj)
     1021           
     1022        seen_objs.execute_update()
    10281023
    1029             # Pre-notify all instances to be deleted.
    1030             for pk_val, instance in items:
    1031                 signals.pre_delete.send(sender=cls, instance=instance)
     1024        seen_objs.execute_delete_related()
     1025       
     1026        seen_objs.reverse_instances()
     1027       
     1028        seen_objs.execute_delete()
    10321029
    1033             pk_list = [pk for pk,instance in items]
    1034             del_query = sql.DeleteQuery(cls, connection)
    1035             del_query.delete_batch_related(pk_list)
     1030        for obj in seen_objs:
     1031            signals.post_delete.send(sender=obj.__class__, instance=obj)
     1032           
     1033        seen_objs.update_instances()
    10361034
    1037             update_query = sql.UpdateQuery(cls, connection)
    1038             for field, model in cls._meta.get_fields_with_model():
    1039                 if (field.rel and field.null and field.rel.to in seen_objs and
    1040                         filter(lambda f: f.column == field.rel.get_related_field().column,
    1041                         field.rel.to._meta.fields)):
    1042                     if model:
    1043                         sql.UpdateQuery(model, connection).clear_related(field,
    1044                                 pk_list)
    1045                     else:
    1046                         update_query.clear_related(field, pk_list)
    1047 
    1048         # Now delete the actual data.
    1049         for cls in ordered_classes:
    1050             items = obj_pairs[cls]
    1051             items.reverse()
    1052 
    1053             pk_list = [pk for pk,instance in items]
    1054             del_query = sql.DeleteQuery(cls, connection)
    1055             del_query.delete_batch(pk_list)
    1056 
    1057             # Last cleanup; set NULLs where there once was a reference to the
    1058             # object, NULL the primary key of the found objects, and perform
    1059             # post-notification.
    1060             for pk_val, instance in items:
    1061                 for field in cls._meta.fields:
    1062                     if field.rel and field.null and field.rel.to in seen_objs:
    1063                         setattr(instance, field.attname, None)
    1064 
    1065                 signals.post_delete.send(sender=cls, instance=instance)
    1066                 setattr(instance, cls._meta.pk.attname, None)
    1067 
    10681035        if forced_managed:
    10691036            transaction.commit()
    10701037        else:

  • django/db/models/query_utils.py

     
    3939    """
    4040
    4141    def __init__(self, previously_seen=None):
     42        # {model: {(field, value): set([instances])}}
     43        self.field_updates = {}
    4244        self.data = {}
    4345        self.children = {}
    4446        if previously_seen:
    45             self.blocked = previously_seen.blocked
    46             for cls, seen in previously_seen.data.items():
    47                 self.blocked.setdefault(cls, SortedDict()).update(seen)
     47            self.blocked = set(previously_seen)
     48            self.blocked.update(previously_seen.blocked)
    4849        else:
    49             self.blocked = {}
     50            self.blocked = set()
    5051
    51     def add(self, model, pk, obj, parent_model, nullable=False):
     52    def add(self, obj, parent_model, nullable=False):
    5253        """
    5354        Adds an item to the container.
    5455
    5556        Arguments:
    56         * model - the class of the object being added.
    57         * pk - the primary key.
    5857        * obj - the object itself.
    5958        * parent_model - the model of the parent object that this object was
    6059          reached through.
    … …  
    6261
    6362        Returns True if the item already existed in the structure and
    6463        False otherwise.
    65         """
    66         if pk in self.blocked.get(model, {}):
     64        """       
     65        if obj in self.blocked:
    6766            return True
    6867
    69         d = self.data.setdefault(model, SortedDict())
    70         retval = pk in d
    71         d[pk] = obj
     68        model = obj.__class__
     69        instances = self.data.setdefault(model, [])
     70        seen_before = obj in instances
     71        if not seen_before:
     72            instances.append(obj)
    7273        # Nullable relationships can be ignored -- they are nulled out before
    7374        # deleting, and therefore do not affect the order in which objects
    7475        # have to be deleted.
    7576        if parent_model is not None and not nullable:
    76             self.children.setdefault(parent_model, []).append(model)
    77         return retval
     77            self.children.setdefault(parent_model, set()).add(model)
     78        return seen_before
     79       
     80    def add_field_update(self, obj, field, value):
     81        updates = self.field_updates.setdefault(obj.__class__, dict())
     82        updates.setdefault((field, value), set()).add(obj)
     83       
     84    def __iter__(self):
     85        for instances in self.data.itervalues():
     86            for obj in instances:
     87                yield obj
    7888
    79     def __contains__(self, key):
    80         return self.data.__contains__(key)
    81 
    82     def __getitem__(self, key):
    83         return self.data[key]
    84 
    8589    def __nonzero__(self):
    8690        return bool(self.data)
    8791
    88     def iteritems(self):
    89         for k in self.ordered_keys():
    90             yield k, self[k]
    91 
    92     def items(self):
    93         return list(self.iteritems())
    94 
    95     def keys(self):
    96         return self.ordered_keys()
    97 
    98     def ordered_keys(self):
    99         """
    100         Returns the models in the order that they should be dealt with (i.e.
    101         models with no dependencies first).
    102         """
    103         dealt_with = SortedDict()
    104         # Start with items that have no children
     92    def sort(self):
     93        for instances in self.data.itervalues():
     94            instances.sort(key=lambda obj: obj.pk)
     95       
     96        sorted_models = []
    10597        models = self.data.keys()
    106         while len(dealt_with) < len(models):
     98        while len(sorted_models) < len(models):
    10799            found = False
    108100            for model in models:
    109                 if model in dealt_with:
     101                if model in sorted_models:
    110102                    continue
    111                 children = self.children.setdefault(model, [])
    112                 if len([c for c in children if c not in dealt_with]) == 0:
    113                     dealt_with[model] = None
     103                children = self.children.get(model)
     104                if not children or not children.difference(sorted_models):
     105                    sorted_models.append(model)
    114106                    found = True
    115107            if not found:
    116                 raise CyclicDependency(
    117                     "There is a cyclic dependency of items to be processed.")
     108                raise CyclicDependency()
     109        self.data = SortedDict([(model, self.data[model]) for model in sorted_models])
    118110
    119         return dealt_with.keys()
     111    def reverse_instances(self):
     112        for instances in self.data.itervalues():
     113            instances.reverse()
    120114
    121     def unordered_keys(self):
    122         """
    123         Fallback for the case where is a cyclic dependency but we don't  care.
    124         """
    125         return self.data.keys()
     115    def execute_delete_related(self):
     116        from django.db.models import connection, sql
     117        for model, instances in self.data.iteritems():
     118            pk_list = [obj.pk for obj in instances]
     119            del_query = sql.DeleteQuery(model, connection)
     120            del_query.delete_batch_related(pk_list)
    126121
     122    def execute_delete(self):
     123        from django.db.models import connection, sql
     124        for model, instances in self.data.iteritems():
     125            pk_list = [obj.pk for obj in instances]
     126            del_query = sql.DeleteQuery(model, connection)
     127            del_query.delete_batch(pk_list)
     128
     129    def execute_update(self):
     130        from django.db.models import connection, sql
     131        from django.db.models.sql.constants import GET_ITERATOR_CHUNK_SIZE
     132        for model, instances_for_fieldvalues in self.field_updates.iteritems():
     133            for (field, value), instances in instances_for_fieldvalues.iteritems():               
     134                pk_field = model._meta.pk
     135                pk_list = [obj.pk for obj in instances]
     136                for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
     137                    query = sql.UpdateQuery(model, connection)
     138                    query.where = query.where_class()
     139                    query.where.add((sql.where.Constraint(None, pk_field.column, pk_field), 'in', pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]), sql.where.AND)
     140                    query.add_update_values({field.name: value})
     141                    query.execute_sql()
     142
     143    def update_instances(self):
     144        for model, instances_for_fieldvalues in self.field_updates.iteritems():
     145            for (field, value), instances in instances_for_fieldvalues.iteritems():
     146                for obj in instances:
     147                    setattr(obj, field.attname, value)
     148        for model, instances in self.data.iteritems():
     149            for instance in instances:
     150                setattr(instance, model._meta.pk.attname, None)
     151
     152
    127153class QueryWrapper(object):
    128154    """
    129155    A type that indicates the contents are an SQL fragment and the associate
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