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

On 9/7/24 14:59, Karsten Hilbert wrote:
> 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 ?

Yes.


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

-- 
Adrian Klaver
adrian.klaver@aklaver.com