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

Am Sat, Sep 07, 2024 at 02:47:49PM -0700 schrieb Adrian Klaver:

> >It is also insufficient because the .commit() itself may
> >elicit exceptions (from the database).
>
> Yeah with Serializable that is part of the package:

No complaints :-)

> > 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.
>
> I'm not following, if you do that then you won't have a commit.

Perhaps my pseudo-code was to abbreviated.

conn = psycopg2.connection()
curs = conn.cursor()
curs.execute(SQL)
curs.close()
conn.commit()
conn.close()

Written more safely:

conn = psycopg2.connection()
curs = conn.cursor()
try:
curs.execute(SQL)
except SOME_PG_EXCEPTION_VIA_PSYCOPG2:
some_panicstricken_logging()
curs.close()
try:
conn.commit()
except SOME_PG_EXCEPTION_VIA_PSYCOPG2__SUCH_AS_SERIALIZATION_ERROR:
some_more_of_the_panicstricken_logging()
conn.close()

now factored out:

def __commit_me_logging_errors(commit_func):
try:
commit_func()
except SOME_PG_EXCEPTION_VIA_PSYCOPG2__SUCH_AS_SERIALIZATION_ERROR:
some_more_of_the_panicstricken_logging()
return

conn = psycopg2.connection()
curs = conn.cursor()
try:
curs.execute(SQL)
except SOME_PG_EXCEPTION_VIA_PSYCOPG2:
some_panicstricken_logging()
curs.close()
__commit_me_logging_errors(conn.commit)
conn.close()

More clear ?

Karsten
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