On Aug 4, 2010, at 11:51 AM, Richard Kuesters wrote:
> thanks Michael, that's what i have in mind. since anon_N can't be used, i was
> thinking if they can be named or, in other cases, the sql that generates an
> anon_N can be extracted?
>
> ps: the object that contains these anon_N columns is a orm.Query object
> created from a polymorphic mapper with multiple relationships.
What I am saying is, they are already extracted, assuming they are appropriate
for use. If these anon's are the product of eagerload()/joinedload(), those
aren't available to you. Otherwise, if you show me the scenario, I will show
you how the anon_1 is available.
>
> On Wed, Aug 4, 2010 at 12:29 PM, Michael Bayer <mike...@zzzcomputing.com>
> wrote:
>
> On Aug 4, 2010, at 10:07 AM, Richard Kuesters wrote:
>
> > hi all,
> >
> > in a polymorphic query, after a 'print' command i realized that SA
> > generates some columns named 'anon_X', which can be helpful for me.
> >
> > the question is:
> >
> > 1. is it safe to use those anon_X columns to refine my query?
> > --- regarding this, my concern is that once the polymorphic query is done
> > by SA, will it anytime change it's name, or anything else in future
> > releases?
>
> it's not. When anonymous aliases are generated within the orm Query against
> some entity that you've given it explicitly, you use the column attributes on
> that entity to reference those columns, not strings. Never use strings
> except for those that you've named explicitly, and at the same level as where
> you named it.
>
> For example, you might use a string if you wanted to ORDER BY some expression
> that's named in the columns clause:
>
> q = sess.query(func.myfunction(...).label('bar')).order_by('bar')
>
> However, once you nest "q" as a subquery, it gains a .c. collection, and now
> you use that .c. collection for all future references to 'bar':
>
> q = q.subquery()
> q2 = sess.query(MyEntity).join((q, q.c.bar==MyEntity.bar))
>
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