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From: Adrian Klaver <[email protected]>
To: Karsten Hilbert <[email protected]>
Cc: [email protected]
Subject: Re: psycopg2: proper positioning of .commit() within try: except: blocks
Date: Sat, 7 Sep 2024 15:09:28 -0700
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
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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
[email protected]

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