Jeff Watkins wrote:
I'm not certain whether the problem I'm about to describe is in
SQLObject or in TurboGears. So I've sent this email to both lists.
I have the following model object:
hub = PackageHub("cms")
__connection__ = hub
class Article(SQLObject,ModelHelper):
slug= StringCol( alternateID=True, length=255 )
sourceFile= StringCol( alternateID=True )
# more stuff
I've created a single Article so far. When I load a fresh tg-admin
shell, and attempt to create a new transaction to manipulate the
article, the following happens:
Python 2.4.1 (#2, Mar 31 2005, 00:05:10)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1666)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from cms.model import *
>>> a= Article.get(1)
>>> a._connection.transaction().begin()
Traceback (most recent call last):
File "<console>", line 1, in ?
File "/Library/Frameworks/Python.framework/Versions/2.4/lib/
python2.4/site-packages/SQLObject-0.7.0-py2.4.egg/sqlobject/
dbconnection.py", line 809, in begin
assert self._obsolete, "You cannot begin a new transaction session
without rolling back this one"
AssertionError: You cannot begin a new transaction session without
rolling back this one
You may well ask why I'm going through the weird hoops to get a
transaction. The answer is I'm working on a generic function which
needs to create a transaction when modifying a model object. The above
is just an example of me trying to puzzle out how SQLObject works.
Can anyone explain to me how a transaction was begun in the snippet above?
Calling .transaction() gives you a transaction connection, that has to
later be used to be of any use. It's already begun, only if you
rollback or commit must you call .begin().
Here's the routine I generally use for transactions:
def do_in_transaction(func, *args, **kw):
old_conn = sqlhub.getConnection()
conn = old_conn.transaction()
sqlhub.threadConnection = conn
try:
try:
value = func(*args, **kw)
except:
conn.rollback()
raise
else:
conn.commit()
return value
finally:
sqlhub.threadConnection = old_conn
This might be a useful addition to the expose decorator. Actually, I
could probably attach the function to ConnectionHub too -- it ought to
exist somewhere in SQLObject.
--
Ian Bicking / [EMAIL PROTECTED] / http://blog.ianbicking.org
