send me a reproducing test case, or at least let me see your
mappings. in particular, dont mix a mapping on a table that is also
used as "secondary" in a many-to-many relationship.
On Apr 17, 2007, at 5:47 PM, chris e wrote:
>
> I'm not sure why. But when I do a delete/sql alchemy seems to be
> running the save/delete operation twice. Could this be related to a
> circular dependency in UOW that is undetected?? When deleting this is
> causing the following error because the database delete is done twice:
>
> sqlalchemy.exceptions.ConcurrentModificationError: Updated rowcount 0
> does not match number of objects updated
>
>
> To fix this I added the following, but it is a serious hack, and
> probably needs to be addressed in the unit of work code, but I'm not
> sure where to look. Code below. I am on 0.3.5, however I tested
> against 0.3.6 as well and this bug appears to be present there as
> well.
>
>
> in orm.unitofwork.UnitOfWork
>
> def _remove_deleted(self, obj):
> if hasattr(obj, "_instance_key"):
>
> # ADDED
> # ignore key errors if the item has already been
> deleted
> try :
> del self.identity_map[obj._instance_key]
> except KeyError:
> pass
> try:
> self.deleted.remove(obj)
> except KeyError:
> pass
> try:
> self.new.remove(obj)
> except KeyError:
> pass
>
>
>
> in orm.mapper.Mapper
>
>
> def delete_obj(self, objects, uowtransaction):
> """issue DELETE statements for a list of objects.
>
> this is called within the context of a UOWTransaction during a
> flush operation."""
>
> if self.__should_log_debug:
> self.__log_debug("delete_obj() start")
>
> connection = uowtransaction.transaction.connection(self)
>
> [self.extension.before_delete(self, connection, obj) for obj
> in objects]
> deleted_objects = util.Set()
> for table in self.tables.sort(reverse=True):
> if not self._has_pks(table):
> continue
> delete = []
> for obj in objects:
>
> # ADDED
> # 4/17/07
> # this prevents items from being deleted twice
> if hasattr(obj, '_has_been_deleted_') :
> continue
>
> params = {}
> if not hasattr(obj, "_instance_key"):
> continue
> else:
> delete.append(params)
> for col in self.pks_by_table[table]:
> params[col.key] = self.get_attr_by_column(obj,
> col)
> if self.version_id_col is not None:
> params[self.version_id_col.key] =
> self.get_attr_by_column(obj, self.version_id_col)
> deleted_objects.add(obj)
> if len(delete):
> def comparator(a, b):
> for col in self.pks_by_table[table]:
> x = cmp(a[col.key],b[col.key])
> if x != 0:
> return x
> return 0
> delete.sort(comparator)
> clause = sql.and_()
> for col in self.pks_by_table[table]:
> clause.clauses.append(col ==
> sql.bindparam(col.key, type=col.type))
> if self.version_id_col is not None:
> clause.clauses.append(self.version_id_col ==
> sql.bindparam(self.version_id_col.key, type=self.version_id_col.type))
> statement = table.delete(clause)
> c = connection.execute(statement, delete)
> if c.supports_sane_rowcount() and c.rowcount !=
> len(delete):
> raise
> exceptions.ConcurrentModificationError("Updated rowcount %d does not
> match number of objects updated %d" % (c.cursor.rowcount,
> len(delete)))
>
> # ADDED
> # this prevents items from being deleted twice
> for obj in deleted_objects :
> obj._has_been_deleted_ = True
> [self.extension.after_delete(self, connection, obj) for obj in
> deleted_objects]
>
>
> >
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