Re: psycopg2: proper positioning of .commit() within try: except: blocks

On 07/09/2024 22:20, Karsten Hilbert via Python-list wrote:

Am Sat, Sep 07, 2024 at 02:09:28PM -0700 schrieb Adrian Klaver:
>

Right, and this was suggested elsewhere ;)
>
And, yeah, the actual code is much more involved :-D
>

I see that.
>
The question is does the full code you show fail?
>
The code sample you show in your original post is doing something very different then
what you show in your latest post. At this point I do not understand the exact problem
we are dealing with.

We are not dealing with an unsolved problem. I had been
asking for advice  where to best place that .commit() call in
case I am overlooking benefits and drawbacks of choices.
>
The
>
try:
do something
except:
log something
finally:
.commit()
>
cadence is fairly Pythonic and elegant in that it ensures the
the .commit() will always be reached regardless of exceptions
being thrown or not and them being handled or not.
>
It is also insufficient because the .commit() itself may
elicit exceptions (from the database).
>
So there's choices:
>
Ugly:
>
try:
do something
except:
log something
finally:
try:
.commit()
except:
log some more
>
Fair but not feeling quite safe:
>
try:
do something
.commit()
except:
log something
>
Boring and repetitive and safe(r):
>
try:
do something
except:
log something
try:
.commit()
except:
log something
>
I eventually opted for the last version, except for factoring
out the second try: except: block.
>
Best,
Karsten
--
GPG  40BE 5B0E C98E 1713 AFA6  5BC0 3BEA AC80 7D4F C89B

Unless I'm missing something, the 1st & 3rd versions always do the commit() even after the first bit fails, which seems wrong.
I suggest the 1st version but replacing "finally" by "else".  Then the try-commit-except will not be executed if the "something" fails.
Perhaps the extra indentation of the second try block is a bit ugly, but it is more important that it does the right thing.
If it is convenient (it may not be) to put the whole thing in a function, you may feel that the follwing is less ugly:
try:
do something
except:
log something
return
try:
.commit()
except:
log some more
return
Best wishes
Rob Cliffe