Foreword: sqlalchemy is really amazing!
Hello,
I'm trying to build a database where users become aware of what has been
changed by other users: there is a SessionExtension that collects info about
changes and then dispatch some messages with a Pyro Event Server.
I'm trying to understand what can be my link point between flush, commit and
rollback operations to store the single IDs into a per-transaction dictionary
and then, when there is a commit on a non-nested transaction, gather all and
dispatch the message through Pyro
I thought I could use id(session.transaction) as a dictionary key, but
- it changes between before_flush and after_flush
- remains the same between before_flush, after_commit and rollback
I need to gather IDs in after_commit because theID is a serial Postgres value
that is available only after flush()
The only correct "link" I found it in an obscure (to me)
_SessionTransaction__parent, so I suspect this is not the "correct" way to
get to my goal. Is there a cleaner way to do such a thing?
Thanks in advance, here is some code:
in mySessionExtension I put:
def after_rollback(self, session):
print "after_rollback", id(session.transaction)
def after_commit(self, session):
print "after_commit", id(session.transaction)
def before_flush(self, session, flush_context, objects):
print "before_flush", id(session.transaction)
def after_flush(self, session, flush_context):
print "after_flush", id(session.transaction),
id(session.transaction._SessionTransaction__parent)
In the main I made:
ss.begin()
rep = dict((x.codice, x) for x in mappers.Reparto.query.all())
r = rep['3']
r.descrizione += '!'
ss.flush()
if 1:
ss.begin_nested()
r = rep['2']
r.descrizione += '!'
ss.flush()
ss.rollback()
ss.commit()
The resulting dump was
before_flush 147722732
after_flush 149425612 147722732
before_flush 149423788
after_flush 149489964 149423788
after_rollback 149423788
after_commit 147722732
I'm working with Python 2.5, SQA 0.4.1 with scoped_session
(transactional=False, autoflush=False)
Thanks
--
Cordialmente
Stefano Bartaletti
Responsabile Software
G.Tosi Spa Tintoria
Skype account: stefano.bartaletti
ICQ contact : 1271960
Viale dell'Industria 61
21052 Busto Arsizio (VA)
Tel. +39 0331 34 48 11
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