I've been staring at this a few hours, and can't figure out how to adapt a join/query into a relationship. The archives and docs don't seem to help much.
It seems reminiscent to an earlier question by Simon King ( https://groups.google.com/d/topic/sqlalchemy/OtI4Z8v7gRs/discussion ) and some of the more advanced relationship docs -- but I fear I'm overthinking this. At the most basic form, I have two tables that can serve as intermediary/association tables to the same tables: class Foo(Base): __tablename__ = 'foo' id = Column(Integer, primary_key=True) class Bar(Base): __tablename__ = 'bar' id = Column(Integer, primary_key=True) class FooBarA(Base): __tablename__ = 'foo_bar_a' id = Column(Integer, primary_key=True) foo_id = Column(Integer, ForeignKey("foo.id"), nullable=False) bar_id = Column(Integer, ForeignKey("bar.id"), nullable= False) class FooBarB(Base): __tablename__ = 'foo_bar_b' id = Column(Integer, primary_key=True) foo_id = Column(Integer, ForeignKey("foo.id"), nullable=False) bar_id = Column(Integer, ForeignKey("bar.id"), nullable= False) i am trying to make the collection of similar relationships available to each association class I was hoping something simple would work: FooBarA.foo_bar_bs = relationship("FooBarB", primaryjoin="and_(FooBarA.foo_id==FooBarB.foo_id, FooBarA.bar_id==FooBarB.bar_id)") FooBarB.foo_bar_as = relationship("FooBarA", primaryjoin="and_(FooBarA.foo_id==FooBarB.foo_id, FooBarA.bar_id==FooBarB.bar_id)") session.query(FooBarB).options(joinedload('foo_bar_a')) session.query(FooBarB).options(subqueryload('foo_bar_a')) But SqlAlchemy wants me to stick to the pattern where primary keys are involved. I totally understand - that stuff is needed for all the advanced collections operations. It looks like I could achieve what I want with some of the examples in the advanced relationships docs, but it looks like it wouldn't be as performance friendly as direct queries, since I'd have to map everything onto the original underlying primary keys. Does anyone know of a more low-impact approach to handling this sort of orm relationship? I think I might just use a @property on the class -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
