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
--
GPG  40BE 5B0E C98E 1713 AFA6  5BC0 3BEA AC80 7D4F C89B