On Sep 22, 2009, at 11:59 AM, Kevin H wrote:
>
> I'm having some trouble developing my model, and was hoping someone on
> this list could help...
>
> Here's what I want:
> A BizEntity object
> A Person and Company object (both descended from BizEntity, using
> joined table inheritance)
> A Company.employees attribute, which points to a list of Persons who
> work for the company
> A Person.company attribute, which points back to the company that
> person works for
>
> Whenever I try to combine inheritance with this sort of pseudo-
> adjacency-list, I get really odd things happening when I try to query
> from the tables...like getting the wrong company back when I query by
> id.
>
> Any ideas out there? Anyone done something like this?
I'm doing this. The first thing to do is to definitely be on 0.5.6
at the least.
the next thing is to define the employees/company thing only once, as
a relation/backref pair on just one of your mapped classes. doing it
twice will mess things up for sure.
your example also mentions a table called "nodes" which from
everything else mentioned below would be erroneous. you don't need
remote_side when mapping between Company and Person.
None of this would cause the wrong "Company" to come back from a
simple query by id, though. If that is really the effect you're
seeing then something more fundamental might be amiss.
>
> MODEL (so far):
> (NOTE: the commented out lines are left over from some of my previous
> attempts to get things working.)
>
> class BizEntity(Base):
> __tablename__ = 'biz_entities'
> id = Column('bizentity_id', Integer, primary_key=True)
> type = Column('bizentity_type', String(30), nullable=False)
> __mapper_args__ = {'polymorphic_on': type}
>
> class Company(BizEntity):
> __tablename__ = 'companies'
> id = Column(Integer, ForeignKey('biz_entities.bizentity_id'),
> primary_key=True)
> name = Column('company_name', String(50))
> #~ employees = relation("Person", backref=backref("company",
> remote_side=[])
> #~ backref('parent', remote_side=[nodes.c.id])
>
> __mapper_args__ = {'polymorphic_identity': 'company'}
>
> class Person(BizEntity):
> __tablename__ = 'people'
> id = Column('bizentity_id', Integer, ForeignKey
> ('biz_entities.bizentity_id'), primary_key=True)
> first_name = Column('first_name', String(50))
> middle_init = Column('middle_init', String(1))
> last_name = Column('last_name', String(50))
>
> #~ company = relation(Company, backref=backref('employees',
> order_by=id))
>
> __mapper_args__ = {'polymorphic_identity':'person'}
>
>
> >
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