On 2 avr, 15:22, [EMAIL PROTECTED] wrote:
> On 2 Apr, 15:15, [EMAIL PROTECTED] wrote:
>
>
>
> > On 2 Apr, 15:12, [EMAIL PROTECTED] wrote:
>
> > > On Apr 2, 3:06 pm, [EMAIL PROTECTED] wrote:
>
> > > > Hi,
>
> > > > I found the following code on the net -
>
> > > > http://mail-archives.apache.org/mod_mbox/httpd-python-cvs/200509.mbox/[EMAIL
> > > > PROTECTED]
>
> > > > def count(self):
> > > > - db = sqlite.connect(self.filename,
> > > > isolation_level=ISOLATION_LEVEL)
> > > > - try:
> > > > - try:
> > > > - cur = db.cursor()
> > > > - cur.execute("select count(*) from sessions")
> > > > - return cur.fetchone()[0]
> > > > - finally:
> > > > - cur.close()
> > > > - finally:
> > > > - db.close()
>
> > > > I don't understand though why the second try is not after the line cur
> > > > = db.cursor(). Can anyone explain for me why?
>
> > > > /Barry.
>
> > > Better question is why is there a try with no except...
>
> > > Better yet, WHY is there two TRY statements when there could quite
> > > happily be only one...
>
> > > Towards what you are asking, I GUESS...because the author hoped to
> > > handle the cases where cur failed to get assigned...but then
> > > his .close method of it would likely not work anyway...I mean...does
> > > this even work...YUCK
>
> > I shouldn't have written "Nested try...except" as the title, instead I
> > mean "Nested try...finally". Sorry about that...
>
> > Anyway, how would you do this? That is, use a finally to close the
> > network connection and the cursor?
>
> > Thanks for your help,
>
> > Barry
>
> Here's what I would do. Is it OK?
>
> def ExecuteWithNoFetching(self, queryString):
>
> sqlServerConnection = adodbapi.connect (";".join (connectors))
slightly OT : where this 'connectors' comes from ?
> try:
> cursor = sqlServerConnection.cursor()
> try:
> cursor.execute(queryString)
> raise Exception("Exception")
> sqlServerConnection.commit()
> finally:
> cursor.close()
> finally:
> sqlServerConnection.close()
Else it looks ok, even if a bit paranoïd. Also, opening a db
connection for each and every single query might not be the best
solution... And finally (no pun intented), this won't let you chain
calls within a single transaction.
Another, a bit more flexible solution could be something like:
def run_in_transaction(*funcs):
sqlServerConnection = adodbapi.connect (";".join (connectors))
try:
cursor = sqlServerConnection.cursor()
try:
for func in funcs:
func(cursor)
except Exception, e:
sqlServerConnection.rollback()
raise
else:
sqlServerConnection.commit()
finally:
cursor.close()
finally:
sqlServerConnection.close()
def do_something(cursor):
cursor.execute("some update query")
def do_something_else(cursor):
cursor.execute("some select query")
for row in cursor.fetchall():
if some_condition(row):
cursor.execute("some update query")
run_in_transaction(do_something, do_something_else)
And also, there's this new 'with' statement...
My 2 cents...
--
http://mail.python.org/mailman/listinfo/python-list
