On Jan 8, 2012, at 2:47 PM, Yuen Ho Wong wrote:
> Hi,
>
> I have a rather complicated problem and I was wondering if you guys
> could help.
>
> So I have a query, session.query(Product, Merchant, d), where Product
> is 1-to-many with Merchant, and d is the distance from some lat long.
> d is actually a sqlalchemy.sql.label() of some complicated GeoAlchemy
> function calls.
>
> Product has a number of collections in which I would like to load
> using subqueryload_all() as well, and the result is ordered by
> "distance" as in order_by("distance"), where "distance" is the name of
> the label d.
>
> My problem is, since I'm supplying the Query object with an explicit
> order_by() name, when I use subqueryload(), the order_by() name is put
> into the subquery as is, because SQLAlchemy doesn't know any better
> with a plain string. If I pass in a column element, SQLAlchemy seems
> to know not to put an ORDER BY in the subquery. This seems to me like
> a bug because a subqueryload() always join on the primary key of the
> previous SELECT, so unless the name is the primary key name, it really
> shouldn't be put in the subquery.
>
> So finally my question, if this is too hard to fix, is there an option
> somewhere that I can tell SA to ignore the previous order_by() when
> doing a subqueryload()? If not, and I can't wait for a fix now, is
> there a way where I can turn my distance label into a ClauseElement so
> that SA knows not to put into the subquery when loading collections?
any chance you can save me some time and attach a complete, succinct .py
example here ? subqueryload removes the ORDER BY from the query, provided
LIMIT/OFFSET aren't present, unconditionally. It doesn't care that it's a
string or not.
http://www.sqlalchemy.org/trac/browser/lib/sqlalchemy/orm/strategies.py#L754
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