On 02/23/2016 06:47 AM, gio wrote:
Hi thanks for your answer
Without filter i did not expect any big difference between
query(Keyword) or a hypothetical query(User.keywords)
but I was thinking it will be nice to do something like this
session.query(User.keywords).filter(User ==4)
without joins..
My goal was to have a simple query that return a structure like the
following
with user and user.keywords
from sqlalchemy import func
myquery = session.query(UserKeyword.user_id,
func.array_agg(UserKeyword.keyword_id)).group_by(UserKeyword.user_id).all()
myquery result [(4, [3, 4]), (3, [1, 2])]
I was thinking associationproxy could help to simplify the ORM
statement but it seems I have to join
OK well the concept of query(Class.somerelationship) as loading that
related entity is a long standing issue we have in bitbucket. It's
strictly a "nice to have" so has not been a priority for some time.
In this case, we're talking about the associationproxy, which means that
we'd also extend that behavior to associationproxy, OK. However, if
someone queried for query(Class.someproxy), again anything built into
SQLAlchemy would at best be query(RelatedClass). What you have there
is a specific series of columns and transformations, e.g. the user_id +
array_agg, which also is database specific too (only works on PG). You
could in theory subclass associationproxy to provide a
__clause_element__() which delivers this part, but it wouldn't
intrinsically do the group_by() part.
The most succinct thing that's easy to do would be if you built a
with_transformation() transformer, so that you could get all the bits
you need done in one step. see
http://docs.sqlalchemy.org/en/rel_1_0/orm/query.html?highlight=with_transformation#sqlalchemy.orm.query.Query.with_transformation
for details on that.
Regards
g
Am Montag, 22. Februar 2016 12:51:55 UTC+1 schrieb gio:
Hi
I was trying to use the associationproxy feature like explained
in the basic example
http://docs.sqlalchemy.org/en/latest/orm/extensions/associationproxy.html
<http://docs.sqlalchemy.org/en/latest/orm/extensions/associationproxy.html>
Now my question is:
Is it possible to do a query like and have as result an array of
array of keywords?
session.query(User.keywords)
Regards
g
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