Hello all,
I've just started using SQLAlchemy recently (and it's been great) but
I have run into a problem recently. I am trying to map a table back to
itself via a second many-to-many table in a declarative fashion. I
have this working as so (mapper configuration):
category_association = Table('BankCategoryMap',
Base.metadata,
Column("ParentCategoryID", Integer,
ForeignKey('BankCategories.ID'), primary_key=True),
Column("ChildCategoryID", Integer,
ForeignKey('BankCategories.ID'), primary_key=True))
category_table = Table('BankCategories',
Base.metadata,
Column("ID", Integer, primary_key=True),
Column("Name", String),
Column("Description", String),
Column("Active", SmallInteger))
class Category(object):
pass
mapper(Category,
category_table,
properties={'parents': relationship(Category,
secondary=category_association,
primaryjoin=category_table.c.ID ==
category_association.c.ChildCategoryID,
secondaryjoin=category_association.c.ParentCategoryID ==
category_table.c.ID,
backref='children')
})
However, when I try it the Declarative way:
category_association = Table('BankCategoryMap',
Base.metadata,
Column("ParentCategoryID", Integer,
ForeignKey('BankCategories.ID'), primary_key=True),
Column("ChildCategoryID", Integer,
ForeignKey('BankCategories.ID'), primary_key=True))
class Category(Base):
__tablename__ = 'BankCategories'
id = Column("ID", Integer, primary_key=True)
name = Column("Name", String)
description = Column("Description", String)
active = Column("Active", SmallInteger)
parents = relationship("Category",
secondary=category_association,
primaryjoin="BankCategories.ID" ==
category_association.c.ChildCategoryID,
secondaryjoin=category_association.c.ParentCategoryID ==
"BankCategories.ID",
backref='children')
This does not work and I get the following error:
File '/home/doug/pyenv_svn/CreateService/surveyservice/surveyservice/
controllers/error.py', line 25 in document
cat.parents
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/attributes.py', line 170 in
__get__
instance_dict(instance))
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/attributes.py', line 390 in
get
value = callable_(passive=passive)
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/strategies.py', line 670 in
__call__
result = q.all()
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/query.py', line 1576 in all
return list(self)
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/query.py', line 1688 in
__iter__
return self._execute_and_instances(context)
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/query.py', line 1693 in
_execute_and_instances
mapper=self._mapper_zero_or_none())
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/session.py', line 729 in
execute
clause, params or {})
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/engine/base.py', line 1191 in
execute
params)
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/engine/base.py', line 1269 in
_execute_clauseelement
parameters=params
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/engine/base.py', line 1377 in
__create_execution_context
connection=self, **kwargs)
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/engine/default.py', line 388 in
__init__
grp,m in enumerate(parameters)]
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/sql/compiler.py', line 291 in
construct_params
pd[self.bind_names[bindparam]] = bindparam.value()
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/strategies.py', line 447 in
<lambda>
state, dict_, bind_to_col[bindparam.key])
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/mapper.py', line 1303 in
_get_state_attr_by_column
return self._columntoproperty[column]._getattr(state, dict_, column,
passive=passive)
File '/home/doug/pyenv_svn/CreateService/lib/python2.6/site-packages/
SQLAlchemy-0.6.5-py2.6.egg/sqlalchemy/orm/mapper.py', line 2510 in
__missing__
(column, self.mapper))
UnmappedColumnError: No column :ChildCategoryID_1 is configured on
mapper Mapper|Category|BankCategories...
Any idea/help on why I'm getting the UnmappedColumnError?
Thanks,
Doug
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