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From: Karsten Hilbert <Karsten.Hilbert@gmx.net>
Newsgroups: comp.lang.python
Subject: Re: psycopg2: proper positioning of .commit() within try: except:
blocks
Date: Sat, 7 Sep 2024 22:45:24 +0200
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Bytes: 12989
Am Sat, Sep 07, 2024 at 01:03:34PM -0700 schrieb Adrian Klaver:
> In the case you show you are doing commit() before the close() so any er=
rors in the
> transactions will show up then. My first thought would be to wrap the co=
mmit() in a
> try/except and deal with error there.
Right, and this was suggested elsewhere ;)
And, yeah, the actual code is much more involved :-D
#------------------------------------------------------------------------
def __safely_close_cursor_and_rollback_close_conn(close_cursor=3DNone, rol=
lback_tx=3DNone, close_conn=3DNone):
if close_cursor:
try:
close_cursor()
except PG_ERROR_EXCEPTION as pg_exc:
_log.exception('cannot close cursor')
gmConnectionPool.log_pg_exception_details(pg_exc)
if rollback_tx:
try:
# need to rollback so ABORT state isn't retained in pooled connections
rollback_tx()
except PG_ERROR_EXCEPTION as pg_exc:
_log.exception('cannot rollback transaction')
gmConnectionPool.log_pg_exception_details(pg_exc)
if close_conn:
try:
close_conn()
except PG_ERROR_EXCEPTION as pg_exc:
_log.exception('cannot close connection')
gmConnectionPool.log_pg_exception_details(pg_exc)
#------------------------------------------------------------------------
def run_rw_queries (
link_obj:_TLnkObj=3DNone,
queries:_TQueries=3DNone,
end_tx:bool=3DFalse,
return_data:bool=3DNone,
get_col_idx:bool=3DFalse,
verbose:bool=3DFalse
) -> tuple[list[dbapi.extras.DictRow], dict[str, int] | None]:
"""Convenience function for running read-write queries.
Typically (part of) a transaction.
Args:
link_obj: None, cursor, connection
queries:
* a list of dicts [{'cmd': <string>, 'args': <dict> or <tuple>)
* to be executed as a single transaction
* the last query may usefully return rows, such as:
SELECT currval('some_sequence');
or
INSERT/UPDATE ... RETURNING some_value;
end_tx:
* controls whether the transaction is finalized (eg.
COMMITted/ROLLed BACK) or not, this allows the
call to run_rw_queries() to be part of a framing
transaction
* if link_obj is a *connection* then "end_tx" will
default to False unless it is explicitly set to
True which is taken to mean "yes, you do have full
control over the transaction" in which case the
transaction is properly finalized
* if link_obj is a *cursor* we CANNOT finalize the
transaction because we would need the connection for that
* if link_obj is *None* "end_tx" will, of course, always
be True, because we always have full control over the
connection, not ending the transaction would be pointless
return_data:
* if true, the returned data will include the rows
the last query selected
* if false, it returns None instead
get_col_idx:
* True: the returned tuple will include a dictionary
mapping field names to column positions
* False: the returned tuple includes None instead of a field mapping dic=
========== REMAINDER OF ARTICLE TRUNCATED ==========