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 [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
