On 20/06/2013 20:43, Michael Bayer wrote:
On Jun 20, 2013, at 1:43 PM, Chris Withers<[email protected]> wrote:
Digging up an old thread, this time with (I hope) correct terminology:
If I have a transient object which has had some attributes set on it, what
would be the best way to use that object to load an object based on those
attributes from the database?
I didn't noticed a session.lookup(myobj) method ;-)
The mapper has all the identity key functions now:
from sqlalchemy import inspect
def lookup(session, obj):
mapper = inspect(obj).mapper
return session.query(mapper).get(mapper.primary_key_from_instance(obj))
a2 = A(id=1)
assert lookup(s, a2) is a1, "%r != %r" % (a1, a2)
That's not what I'm after ;-)
The query needed to get the unit test to pass, as I would currently do
it, would be:
def lookup(self):
return session.query(Model).filter(
value1=self.value1
).one()
...but I'm looking to generalise that to any attribute that has been set
on the transient object on which lookup is called.
cheers,
Chris
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