Hi
I'd like to setup a small versioning extension. Thus I set up a
MepperExtension an overwitten the instrument_class method:
class VersionExtension(MapperExtension):
"""
With this extension it should be possible to load a versioned
entity with:
>>>
db.session.query(Address).filter_by(valid_at=datetime.date.today()).all()
Declaring a versioned object is done by calling
versioned_entity(allow_overlap=False) method.
When passing allow_overlap=True there can be multiple versions of
this entity at the same
time.
"""
def instrument_class(self, mapper, clazz):
mapper.add_property('valid_from',
ColumnProperty(Column('valid_from', DateTime, nullable=False)))
mapper.add_property('valid_to',
ColumnProperty(Column('valid_to', DateTime, nullable=True)))
class ValidComparator(PropComparator):
def __eq__(self, other):
valid_at = self.__clause_element__()
clazz = mapper.class_
return and_(
or_(
and_(clazz.valid_from<=valid_at,
clazz.valid_to>=valid_at),
and_(clazz.valid_from<=valid_at,
clazz.valid_to==None),
)
)
mapper.add_property('valid_at',
ComparableProperty(ValidComparator))
return EXT_CONTINUE
The problem is, this fails with the error >> AttributeError: 'Mapper'
object has no attribute 'columns' [1]
Did anyone encounter this problem as well or does anyone know what I'm
doing wrong?
Regards,
Florian
[1]
Traceback (most recent call last):
File "/Users/fm/dev/wlib/roopio/src/roopio/tests/regressiontests/
test_versioning.py", line 56, in test_versioned
class Entity(db.Base):
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/ext/
declarative.py", line 1231, in __init__
_as_declarative(cls, classname, cls.__dict__)
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/ext/
declarative.py", line 1224, in _as_declarative
**mapper_args)
File "/Users/fm/dev/wlib/wlib/src/wlib/db/__init__.py", line 35, in
mapper
return orm.mapper(cls, *args, **kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/orm/
__init__.py", line 861, in mapper
return Mapper(class_, local_table, *args, **params)
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/orm/
mapper.py", line 215, in __init__
self._configure_class_instrumentation()
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/orm/
mapper.py", line 391, in _configure_class_instrumentation
self.extension.instrument_class(self, self.class_)
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/orm/
util.py", line 241, in _do
ret = getattr(ext, method)(*args, **kwargs)
File "/Users/fm/dev/wlib/roopio/src/roopio/tests/regressiontests/
test_versioning.py", line 24, in instrument_class
mapper.add_property('valid_from',
ColumnProperty(Column('valid_from', DateTime, nullable=False)))
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/orm/
mapper.py", line 857, in add_property
self._configure_property(key, prop, init=self.compiled)
File "/Library/Frameworks/Python.framework/Versions/3.1/lib/
python3.1/site-packages/SQLAlchemy-0.6.5-py3.1.egg/sqlalchemy/orm/
mapper.py", line 730, in _configure_property
self.columns[key] = col
AttributeError: 'Mapper' object has no attribute 'columns'
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