I receive "AttributeError: '_ProxyImpl' object has no attribute
'get_history'" when attempting to use session.is_modified on a class
with a synonym with a descriptor. Removing the descriptor from the
synonym prevents the error. Code and full traceback below.
#################################################
from sqlalchemy import Table, Column, Integer, String, MetaData,
create_engine, ForeignKey
from sqlalchemy.orm import relation, sessionmaker, scoped_session,
mapper, synonym, object_session
from sqlalchemy.orm.interfaces import MapperExtension
class SynonymProp(object):
def __init__(self, attribute):
self._attribute = attribute
def __set__(s, obj, value):
setattr(obj, s._attribute, value)
def __delete__(s, obj):
delattr(obj, s._attribute)
def __get__(s, obj, owner):
if obj is None:
return s
return getattr(obj, s._attribute)
class Extension(MapperExtension):
def before_update(self, mapper, connection, instance):
object_session(instance).is_modified(instance,
include_collections=False)
engine = create_engine('sqlite:///', echo=False)
Session = scoped_session(sessionmaker(autoflush=True,
autocommit=False, bind=engine))
metadata = MetaData()
bananas = Table('bananas', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(35)))
class Banana(object): pass
mapper(Banana, bananas, extension=Extension(), properties={
'name': synonym('_name', map_column=True, descriptor=SynonymProp
('_name'))
})
metadata.create_all(bind=engine)
b1 = Banana()
Session.add(b1)
Session.commit()
b1.name = 'Bob'
Session.commit()
#################################################
Traceback (most recent call last):
File "sa_test.py", line 50, in <module>
Session.commit()
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\scoping.py", line 121, in do
return getattr(self.registry(), name)(*args, **kwargs)
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\session.py", line 673, in commit
self.transaction.commit()
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\session.py", line 378, in commit
self._prepare_impl()
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\session.py", line 362, in _prepare_impl
self.session.flush()
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\session.py", line 1354, in flush
self._flush(objects)
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\session.py", line 1432, in _flush
flush_context.execute()
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\unitofwork.py", line 257, in execute
UOWExecutor().execute(self, tasks)
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\unitofwork.py", line 720, in execute
self.execute_save_steps(trans, task)
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\unitofwork.py", line 735, in
execute_save_steps
self.save_objects(trans, task)
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\unitofwork.py", line 726, in save_objects
task.mapper._save_obj(task.polymorphic_tosave_objects, trans)
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\mapper.py", line 1251, in _save_obj
mapper.extension.before_update(mapper, connection, state.obj())
File "c:\program files\python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\util.py", line 234, in _do
ret = getattr(ext, method)(*args, **kwargs)
File "sa_test.py", line 22, in before_update
object_session(instance).is_modified(instance,
include_collections=False)
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\session.py", line 1483, in is_modified
(added, unchanged, deleted) = attr.get_history(instance,
passive=passive)
File "C:\PROGRA~1\Python\lib\site-packages\sqlalchemy-0.5.4p2-
py2.5.egg\sqlalchemy\orm\attributes.py", line 108, in get_history
return self.impl.get_history(instance_state(instance),
instance_dict(instance), **kwargs)
AttributeError: '_ProxyImpl' object has no attribute 'get_history'
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