well, a "default", I disagree the problem is that simple. Because we
have a "default", Mapper.order_by, but all those cases I mentioned, no idea.
If we wanted to say that hey, "default" only means, "I'm querying for a
single entity in full, alone, otherwise no order_by", I guess that's
something. I can un-deprecate mapper.order_by if people wanted to
really work out what it should do always.
Anyway, if "default" is really something kind of arbitrary here, you can
use the before_compile event hook for Query.
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import event
Base = declarative_base()
class A(Base):
__tablename__ = 'a'
id = Column(Integer, primary_key=True)
default_order_by = {
A: A.id
}
@event.listens_for(Query, "before_compile", retval=True)
def _default_order_by(query):
entity = query.column_descriptions[0]['entity']
if entity in default_order_by:
query = query.order_by(default_order_by[entity])
return query
e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)
s = Session(e)
s.add_all([A(id=1), A(id=2)])
s.commit()
s.query(A).all()
On 05/09/2017 03:36 AM, Chris Withers wrote:
Gotcha. Is there any way to specify a default ordering for queries
against a model?
(similar to that offered by the Django ORM?)
cheers,
Chris
On 08/05/2017 23:51, mike bayer wrote:
because, it only works for a really simplistic case, and for all the
other cases, I have no idea what it currently does, nor what it should
do.
Assume A and B have order_by. I have no idea what the output is, or
should be, for:
s.query(A, B)
s.query(B, A)
s.query(A).join(B)
s.query(A).select_from(B).join(A)
s.query(A, B).select_from(B).join(A)
s.query(A.id)
s.query(A, B.id)
s.query(A.id, B)
s.query(A.id, B.id)
s.query(B.id, A.id)
etc
On 05/08/2017 06:21 AM, Chris Withers wrote:
Hi All,
I see mapper.order_by is deprecated in the latest release. Why is that?
cheers,
Chris
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