On Nov 10, 2008, at 12:08 PM, John Hunter wrote:
>
> On Mon, Nov 10, 2008 at 10:05 AM, King Simon-NFHD78
> <[EMAIL PROTECTED]> wrote:
>
>> Actually, the section after that (Using Subqueries) probably does
>> something very close to what you want. What's the result of these
>> lines:
>>
>> q1 = (session.query(Snapshot.strategy, Snapshot.symbol, sum_pnl)
>> .group_by(Snapshot.strategy, Snapshot.symbol)
>> .having(sum_pnl<-15000)).subquery()
>>
>> q2 = (session.query(Snapshot.strategy, func.count('*'))
>> .join(q1, Snapshot.strategy = q1.c.strategy)
>> .groupby(Snapshot.strategy))
>
>
> I assume you mean '=='? I get a foreign key error on the join::
>
> sum_pnl = func.sum(Snapshot.pnl)
>
> q1 = (session.query(Snapshot.strategy, Snapshot.symbol, sum_pnl)
> .group_by(Snapshot.strategy, Snapshot.symbol)
> .having(sum_pnl<-15000)).subquery()
>
> q2 = (session.query(Snapshot.strategy, func.count('*'))
> .join(q1, Snapshot.strategy==q1.c.strategy)
> .groupby(Snapshot.strategy))
>
> File "/home/titan/johnh/dev/lib/python2.4/site-packages/
> SQLAlchemy-0.5.0rc3dev_r5205-py2.4.egg/sqlalchemy/sql/util.py",
> line 109, in join_condition
> raise exc.ArgumentError(
> ArgumentError: Can't find any foreign key relationships between
> 'snapshot' and '{ANON 157186924 anon}'
>
> Still playing with the aliases in the link you referred me to above
> but haven't gotten there yet...
>
you need an extra tuple on the join, query.join((q1, s.s==q1.c.s))
i think I might need to look into raising an error when the arguments
aren't sent properly, im not sure why it doesn't do that already.
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