On 19/02/14 16:01, Michael Bayer wrote:
On Feb 19, 2014, at 1:34 PM, Mariano Mara <mariano.m...@gmail.com> wrote:
On 19/02/14 15:28, Michael Bayer wrote:
On Feb 19, 2014, at 1:14 PM, Mariano Mara <mariano.m...@gmail.com> wrote:
# relationships
runner = relationship("User", foreign_keys=[uid, oid],
#primaryjoin=and_("Bet.uid==User.uid",
"Bet.oid==User.oid"),
)
loader = relationship("User", foreign_keys=[loader_uid, oid])
you've got the quoting off on that commented-out primaryjoin, here's the most
direct way to set it up:
runner = relationship("User",
primaryjoin="and_(foreign(Bet.uid)==User.uid,
foreign(Bet.oid)==User.oid)",
)
loader = relationship("User",
primaryjoin="and_(foreign(Bet.loader_uid)==User.uid,
foreign(Bet.oid)==User.oid)",
)
I have tried with the primaryjoin too (although not including the foreign())
and I hit a different error. Your suggestion -of course- works.
I am confuse now: when do I use the primaryjoin and/or foreign_keys and/or
foreign?
well these approaches are largely interchangeable in the vast majority of cases. your schema here is
actually throwing two curveballs at once, one is the usual "more than one foreign key constraint"
problem, but the other is that two of these constraints actually share the same column. For example I can
also set foreign_keys=[loader_uid] / foreign_keys=[uid], and it configures, because the 'oid' column isn't
there to confuse things, but then "oid" isn't taken into account. Really, SQLA's "here's how
i figure things out based on foreign key" logic is not quite ready for that specific set of inputs. I'll
add a bug report for it.
the approach of primaryjoin with foreign() is the most specific method which
leaves the least amount of questions for SQLAlchemy to figure out.
Crystal clear. Thanks for your answer and time. I really appreciate it.
Mariano
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