By chance, in your mappers, are you declaring two relationships instead of one
relation with a backref?
As a side note, once you straighten this out, you may want to declare the
composite (a_id, b_id) as a unique key on the relation table.
Barry
----- Original Message ----
From: Karlo Lozovina <[EMAIL PROTECTED]>
To: sqlalchemy <sqlalchemy@googlegroups.com>
Sent: Sunday, May 4, 2008 4:31:55 PM
Subject: [sqlalchemy] Duplication of rows in many-to-many relationship
Let's say I have two classes A and B, and I want instances of both
classes, to have a list of each other, that is, many-to-many
relationship. For a shorthand, "a" means instance of A, and "b" is an
instance of B.
For example: "a.bs" is a list, full of instances of class B.
Similarly, "b.as" is a list, full of instances of class A. In
modelling that relationship I use three tables, one for As, one for
Bs, and one for their relationship. If I only append instances of B to
some "a.bs", then save all those objects, everything works fine. But
if I append instances of A and B, both to "a.bs" and "b.as", then
save, I get double rows in the third table. Is there a way around
that?
P.S.
In a very likely case I haven't been completely understood, I'll
attach some code to demonstrate my point ;).
Thanks all.
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