Hello,
I am porting my code to SA 0.4 and cannot figure out whether or not I should
work correctly.
I have most of my db-related code united under a single DatabaseFacade class
which is then bound to SA session via property:
class DatabaseFacade(object):
...
session = property(fget=lambda self: Session())
Session is setup as:
Session = scoped_session(sessionmaker(autoflush=True, transactional=True))
and configured later on.
Here is how I use it:
def create_draft(self, **kw):
p = WordpressPost(**kw)
self.session.save(p)
self.session.commit()
return p
Since self.session is a property it calls Session() repeatedly. It seems to
work but is it OK, from transactional/performance point of view?
Do I need to change it to something like:
s = self.session # obtain new session
s.save(p)
s.commit()
I also have a transactional_method() decorator which does session().begin()
and then commit() or rollback() depending on whether exception occured or
not.
I also noticed that session.save() fails if I try to save a "persistent"
object so I am forced to change every such save() call to save_or_update().
I don't mind but why it's not mentioned in whatsnew40/migration guide?
Another error I am now getting is:
InvalidRequestError: Instance '[EMAIL PROTECTED]' is with key (<class '
doupy.model.objects.Invoice'>, (73L,), None) already persisted with a
different identity
Any ideas how to fix this?
Method impl. looks lke this (edited for brevity):
@transactional_method()
def create_invoice(self, wpuser, **kw):
invoice = Invoice(wpuser, public_id=str(next_id), **kw)
self.session.save(invoice)
return invoice
Btw, is it possible to retrieve metadata if you have an engine or configured
session object? I haven't found a way so ended up storing it in a module
global when session is configured.
--
Max
http://maxischenko.in.ua // http://www.linkedin.com/in/maksim
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