You can call query.subquery().as_scalar() for now. My problem with "as_scalar()" is that I hate the name, but "scalar()" is already taken.
On Sep 1, 2010, at 1:32 AM, Russell Warren wrote: > Another question on this... > > Is there any particular reason that orm.query objects don't have > as_scalar methods? > > While trying to hack around and figure out how to make this work, one > thing I definitely tried was substituting one-item-result queries in > as scalar replacement values in a similar fashion to the select you > showed. It did not work because Query objects are not accepted as > binding parameters even if they only have one column. If there were > an equivalent "as_scalar" call on a query as what exists for the > Select object, it seems like this type of scalar variable substitution > could be cleanly done and remain in the ORM frame of mind. > > To demonstrate the obvious equivalence, below is a small comparison... > >>>> s = select([User.id]).where(User.name == 'jack') >>>> q = sess.query(User.id).filter(User.name == "jack") >>>> print s > SELECT users.id > FROM users > WHERE users.name = :name_1 >>>> print q > SELECT users.id AS users_id > FROM users > WHERE users.name = :name_1 >>>> s.as_scalar() > <sqlalchemy.sql.expression._ScalarSelect at 0x1a40a90; Select object> >>>> q.as_scalar() > Traceback (most recent call last): > File "<string>", line 1, in <fragment> > AttributeError: 'Query' object has no attribute 'as_scalar' > > > If queries had as_scalar(), the equivalent way to add an address with > one query would just be... > > uid = sess.query(User.id).filter(User.name == "jack").as_scalar() > sess.add(Address(user_id = uid, > email_address = 'blah')) > > which is 100% readable and logical to me, at least from a usage > perspective. You would just need to know about the as_scalar method. > > Having said that, the more I look at the combo ORM+select way, that is > also quite logical and readable. I just need to burn into my mind > that the base sql toolkit and orm work really nicely together and that > I don't necessarily need to stick to one side of the fence. > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalch...@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
