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Re: Newbie needing some help

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On Fri, Aug 8, 2014 at 4:38 PM, Chris Angelico <rosuav@gmail.com> wrote:

> On Sat, Aug 9, 2014 at 8:01 AM, Chris Kaynor <ckaynor@zindagigames.com>
> wrote:
> > However, I'd recommend re-raising the exception after rolling back the
> > transaction with a bare "raise" statement right after the db.rollback()
> - at
> > the absolute minimum, you should log the error. This will likely let you
> see
> > what your problem is.
>
> AIUI, aborting the process with an uncaught exception would roll back
> implicitly, so there's no need to "bare except, roll back, bare
> raise". But even if that's not the case, I would be looking at a
> try/finally for this, rather than a try/except/raise.
>

I would imagine that on connection close, the server would rollback any
uncommitted transactions, however that presumes that the connection close
is completed in a reasonably timely manner (with a try...finally for
closing, it should be).

This is one case where I think try...except/raise is better than
try...finally. If you use try...finally to rollback, you'd have to either
track whether you committed, or you'd rollback with no actions (or possibly
a committed action, which could have odd behavior, depending on the
implementation)

try:
    action
    commit
except:
    rollback
    raise

I feel is better than:

try:
    action
    commit
finally:
    rollback

or:

success = False
try:
    action
    commit
    success = True
finally:
    if success:
        rollback

and is very different than:

try:
    action
finally:
    commit

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Re: Newbie needing some help Chris Kaynor <ckaynor@zindagigames.com> - 2014-08-08 16:55 -0700

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