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From: Karsten Hilbert <Karsten.Hilbert@gmx.net>
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Subject: Re: psycopg2: proper positioning of .commit() within try: except:
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Am Sun, Sep 08, 2024 at 02:58:03PM +0100 schrieb Rob Cliffe via Python-lis=
t:

> >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.

> Unless I'm missing something, the 1st & 3rd versions always do the commi=
t() even after
> the first bit fails, which seems wrong.

Well, it does run a Python function called "commit". That
function will call "COMMIT" on the database. The end result
will be correct (at the SQL level) because the COMMIT will
not effect a durable commit of data when the SQL in "do
something" had failed.

We have, however, elicited that there may well be other
things belonging into the running business level transaction
which may fail and which should lead to data not being
committed despite being technically correct at the SQL level.

> I suggest the 1st version but replacing "finally" by "else".=A0 Then the=
 try-commit-except
> will not be executed if the "something" fails.

The whole point was to consolidate the commit into one place.
It is unfortunately named, though. It should be called
"close_transaction".

> 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:

The whole thing does reside inside a function but the exit-early pattern
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