werner wrote:
> In my model I have:
>
> class Country(BaseExt):
> pass
>
> sao.mapper(Country, createSelect(Country_D, Country_T, 'countries_d_id',
> ['name', 'url']))
>
> Which I can use like this:
>
> for cs in session.query(db.Country).all():
> print cs.name, cs.id
>
> But I run into problems when I try to use "Country" in a relation like
> this:
>
> class Region_D(Base, CreateUpdateMixin):
> __tablename__ = u'regions_d'
>
> id = sa.Column(sa.Integer(), sa.Sequence('regions_d_id'),
> primary_key=True, nullable=False)
> name = sa.Column(sa.String(length=50, convert_unicode=False))
>
> countries_d_id = sa.Column(sa.Integer())
>
> country = sao.relation('Country', backref='region_d',
> primaryjoin='Region_D.countries_d_id == Country.id')
>
> I am getting this exception also "Country" is defined before "Region_D":
if you use "'Country'" as a string in relation(), the declarative base
looks for it inside of Base._decl_class_registry. Its not here since
Country isn't part of Base. You should be saying "Country", i.e. send
the actual class, to the relation().
>
> Traceback (most recent call last):
> File "saTest.py", line 41, in <module>
> for cs in session.query(db.Country).all():
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\session.py",
> line 893, in query
> return self._query_cls(entities, self, **kwargs)
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\query.py",
> line 92, in __init__
> self._set_entities(entities)
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\query.py",
> line 101, in _set_entities
> self._setup_aliasizers(self._entities)
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\query.py",
> line 115, in _setup_aliasizers
> mapper, selectable, is_aliased_class = _entity_info(entity)
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\util.py",
> line 492, in _entity_info
> mapper = class_mapper(entity, compile)
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\util.py",
> line 567, in class_mapper
> mapper = mapper.compile()
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\mapper.py",
> line 687, in compile
> mapper._post_configure_properties()
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\mapper.py",
> line 716, in _post_configure_properties
> prop.init()
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\interfaces.py",
> line 408, in init
> self.do_init()
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\properties.py",
> line 714, in do_init
> self._get_target()
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\orm\properties.py",
> line 731, in _get_target
> self.mapper = mapper.class_mapper(self.argument(), compile=False)
> File
> "c:\python25\lib\site-packages\sqlalchemy-0.5.8-py2.5.egg\sqlalchemy\ext\declarative.py",
> line 624, in return_cls
> prop.parent, arg, n.args[0], cls))
> sqlalchemy.exc.InvalidRequestError: When compiling mapper
> Mapper|Region_D|regions_d, expression 'Country' failed to locate a name
> ("name 'Country' is not defined"). If this is a class name, consider
> adding this relation() to the <class 'model.Region_D'> class after both
> dependent classes have been defined.
>
> Am I doing something wrong or is it not possible to use a class/mapper
> based on a select in a relation?
>
> Werner
>
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