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Anonymous committed e5a84a2

Backport generic-relations data loss fix from [4428]. Thanks to Malcolm for pointing out my stupid error the first time I tried this.

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Files changed (2)

django/db/models/query.py

 from django.db import backend, connection, transaction
 from django.db.models.fields import DateField, FieldDoesNotExist
+from django.db.models.fields.generic import GenericRelation
 from django.db.models import signals
 from django.dispatch import dispatcher
 from django.utils.datastructures import SortedDict
 
         pk_list = [pk for pk,instance in seen_objs[cls]]
         for related in cls._meta.get_all_related_many_to_many_objects():
+            if not isinstance(related.field, GenericRelation):
+                for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
+                    cursor.execute("DELETE FROM %s WHERE %s IN (%s)" % \
+                                   (qn(related.field.m2m_db_table()),
+                                    qn(related.field.m2m_reverse_name()),
+                                    ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])),
+                                   pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE])
+        for f in cls._meta.many_to_many:
+            if isinstance(f, GenericRelation):
+                from django.contrib.contenttypes.models import ContentType
+                query_extra = 'AND %s=%%s' % f.rel.to._meta.get_field(f.content_type_field_name).column
+                args_extra = [ContentType.objects.get_for_model(cls).id]
+            else:
+                query_extra = ''
+                args_extra = []
             for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
                 cursor.execute("DELETE FROM %s WHERE %s IN (%s)" % \
-                    (qn(related.field.m2m_db_table()),
-                        qn(related.field.m2m_reverse_name()),
-                        ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])),
-                    pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE])
-        for f in cls._meta.many_to_many:
-            for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):
-                cursor.execute("DELETE FROM %s WHERE %s IN (%s)" % \
-                    (qn(f.m2m_db_table()), qn(f.m2m_column_name()),
-                    ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])),
-                    pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE])
+                               (qn(f.m2m_db_table()), qn(f.m2m_column_name()),
+                                ','.join(['%s' for pk in pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE]])) + query_extra,
+                               pk_list[offset:offset+GET_ITERATOR_CHUNK_SIZE] + args_extra)
         for field in cls._meta.fields:
             if field.rel and field.null and field.rel.to in seen_objs:
                 for offset in range(0, len(pk_list), GET_ITERATOR_CHUNK_SIZE):

tests/modeltests/generic_relations/models.py

 
 # Objects with declared GenericRelations can be tagged directly -- the API
 # mimics the many-to-many API.
+>>> bacon.tags.create(tag="fatty")
+<TaggedItem: fatty>
+>>> bacon.tags.create(tag="salty")
+<TaggedItem: salty>
 >>> lion.tags.create(tag="yellow")
 <TaggedItem: yellow>
 >>> lion.tags.create(tag="hairy")
 <TaggedItem: hairy>
->>> bacon.tags.create(tag="fatty")
-<TaggedItem: fatty>
->>> bacon.tags.create(tag="salty")
-<TaggedItem: salty>
 
 >>> lion.tags.all()
 [<TaggedItem: hairy>, <TaggedItem: yellow>]
 [<TaggedItem: shiny>]
 >>> TaggedItem.objects.filter(content_type__pk=ctype.id, object_id=quartz.id)
 [<TaggedItem: clearish>]
+
+
+# If you delete an object with an explicit Generic relation, the related 
+# objects are deleted when the source object is deleted. 
+# Original list of tags: 
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()] 
+[('clearish', <ContentType: mineral>, 1), ('fatty', <ContentType: vegetable>, 2), ('hairy', <ContentType: animal>, 1), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2), ('yellow', <ContentType: animal>, 1)]
+ 
+>>> lion.delete() 
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()] 
+[('clearish', <ContentType: mineral>, 1), ('fatty', <ContentType: vegetable>, 2), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2)]
+ 
+# If Generic Relation is not explicitly defined, any related objects  
+# remain after deletion of the source object. 
+>>> quartz.delete() 
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()] 
+[('clearish', <ContentType: mineral>, 1), ('fatty', <ContentType: vegetable>, 2), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2)]
+ 
+# If you delete a tag, the objects using the tag are unaffected  
+# (other than losing a tag) 
+>>> tag = TaggedItem.objects.get(id=1) 
+>>> tag.delete() 
+>>> bacon.tags.all() 
+[<TaggedItem: salty>]
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()] 
+[('clearish', <ContentType: mineral>, 1), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2)]
+
 """