Ticket #10262: delete_cascade_option_with_tests_r9834.diff

tests/modeltests/delete/models.py

@@ -40 +40 @@
 class F(DefaultRepr, models.Model):
     e = models.ForeignKey(E, related_name='f_rel')
 
+# Standard many to one and one to one relation, with no delete cascade behaviour
+class G(DefaultRepr, models.Model):
+    pass
 
+class H(DefaultRepr, models.Model):
+    g = models.ForeignKey(G, null=True, delete_cascade=False)
+
+class I(DefaultRepr, models.Model):
+    h = models.OneToOneField(H, null=True, delete_cascade=False)
+
 __test__ = {'API_TESTS': """
 ### Tests for models A,B,C,D ###
 
@@ -186 +195 @@
 
 >>> f2.delete()
 
+# Testing non delete cascade behaviour.
+
+>>> g1 = G()
+>>> g1.save()
+>>> h1 = H(g=g1)
+>>> h1.save()
+>>> g1.delete()
+>>> H.objects.count()
+1
+
+>>> i = I(h=h1)
+>>> i.save()
+>>> h1.delete()
+>>> I.objects.count()
+1
+
 """
 }

django/db/models/base.py

@@ -11 +11 @@
 import django.db.models.manager     # Imported to register signal handler.
 from django.core.exceptions import ObjectDoesNotExist, MultipleObjectsReturned, FieldError
 from django.db.models.fields import AutoField, FieldDoesNotExist
-from django.db.models.fields.related import OneToOneRel, ManyToOneRel, OneToOneField
+from django.db.models.fields.related import OneToOneRel, ManyToOneRel, OneToOneField, RelatedObject
 from django.db.models.query import delete_objects, Q, CollectedObjects
 from django.db.models.options import Options
 from django.db import connection, transaction, DatabaseError
@@ -456 +456 @@
     def delete(self):
         assert self._get_pk_val() is not None, "%s object can't be deleted because its %s attribute is set to None." % (self._meta.object_name, self._meta.pk.attname)
 
+        # Clear all related objects with no delete cascade relation behaviour
+        related_objects_updated = False
+        for field in self._meta.get_all_fields():
+            if isinstance(field, RelatedObject) and \
+               isinstance(field.field.rel, ManyToOneRel) and \
+               not field.field.rel.delete_cascade:
+                if isinstance(field.field.rel, OneToOneRel):
+                    try:
+                        rel_obj = getattr(self, field.get_accessor_name())
+                        setattr(rel_obj, field.field.name, None)
+                        rel_obj.save()
+                    except ObjectDoesNotExist:
+                        pass # nothing to do
+                else: # ManyToOneRel
+                    related_manager = getattr(self, field.get_accessor_name())
+                    related_manager.clear()
+                related_objects_updated = True
+        if related_objects_updated:
+            # we ensure that refill related object cache
+            del self._meta._related_objects_cache
+
         # Find all the objects than need to be deleted.
         seen_objs = CollectedObjects()
         self._collect_sub_objects(seen_objs)

django/db/models/options.py

@@ -283 +283 @@
             raise FieldDoesNotExist('%s has no field named %r'
                     % (self.object_name, name))
 
+    def get_all_fields(self):
+        """
+        Returns a list of all fields that are possible for this model
+        (including reverse relation names).
+        """
+        try:
+            cache = self._name_map
+        except AttributeError:
+            cache = self.init_name_map()
+        fields = [ r[0] for r in cache.values() ]
+        return fields
+
     def get_all_field_names(self):
         """
         Returns a list of all field names that are possible for this model

django/db/models/fields/related.py

@@ -583 +583 @@
         manager.add(*value)
 
 class ManyToOneRel(object):
-    def __init__(self, to, field_name, related_name=None,
-            limit_choices_to=None, lookup_overrides=None, parent_link=False):
+    def __init__(self, to, field_name, related_name=None, limit_choices_to=None,
+            lookup_overrides=None, parent_link=False, delete_cascade=True):
         try:
             to._meta
         except AttributeError: # to._meta doesn't exist, so it must be RECURSIVE_RELATIONSHIP_CONSTANT
@@ -597 +597 @@
         self.lookup_overrides = lookup_overrides or {}
         self.multiple = True
         self.parent_link = parent_link
+        self.delete_cascade = delete_cascade
 
     def get_related_field(self):
         """
@@ -610 +611 @@
         return data[0]
 
 class OneToOneRel(ManyToOneRel):
-    def __init__(self, to, field_name, related_name=None,
-            limit_choices_to=None, lookup_overrides=None, parent_link=False):
+    def __init__(self, to, field_name, related_name=None, limit_choices_to=None,
+            lookup_overrides=None, parent_link=False, delete_cascade=True):
         super(OneToOneRel, self).__init__(to, field_name,
                 related_name=related_name, limit_choices_to=limit_choices_to,
-                lookup_overrides=lookup_overrides, parent_link=parent_link)
+                lookup_overrides=lookup_overrides, parent_link=parent_link,
+                delete_cascade=delete_cascade)
         self.multiple = False
 
 class ManyToManyRel(object):
@@ -645 +647 @@
             related_name=kwargs.pop('related_name', None),
             limit_choices_to=kwargs.pop('limit_choices_to', None),
             lookup_overrides=kwargs.pop('lookup_overrides', None),
-            parent_link=kwargs.pop('parent_link', False))
+            parent_link=kwargs.pop('parent_link', False),
+            delete_cascade=kwargs.pop('delete_cascade', True))
+
         Field.__init__(self, **kwargs)
 
         self.db_index = True
+        assert self.null or self.rel.delete_cascade, "%s cannot define a not null relation (null=False) without deleting cascade (delete_cascade=False)" % self.__class__.__name__
 
     def get_attname(self):
         return '%s_id' % self.name

django/contrib/admin/util.py

@@ -71 +71 @@
         if related.opts in opts_seen:
             continue
         opts_seen.append(related.opts)
+        if not related.field.rel.delete_cascade:
+            # Avoid deleting objects without a delete cascade relation
+            continue
         rel_opts_name = related.get_accessor_name()
+
         if isinstance(related.field.rel, models.OneToOneRel):
             try:
                 sub_obj = getattr(obj, rel_opts_name)