Marc-Andre Lemburg <m...@egenix.com> added the comment: On 08.01.2022 21:56, Erlend E. Aasland wrote: > > Marc-André: since Python 3.6, the sqlite3.Cursor.lastrowid attribute does no > longer comply with the recommendations of PEP 249: > > Previously, lastrowid was set to None for operations other than INSERT or > REPLACE. This changed with ab994ed8b97e1b0dac151ec827c857f5e7277565 (in > Python 3.6), so that lastrowid is _unchanged_ for operations other than > INSERT or REPLACE, and it is set to 0 after the first valid SQL (that is not > INSERT/REPLACE) is executed on the cursor. > > Now, PEP 249 only _recommends_ that lastrowid is set to None for operations > that do not modify a row, so it's probably not a big deal. No-one has ever > mentioned this change in behaviour; there have been no bug reports. > > FTR, here is the relevant quote from PEP 249: > > If the operation does not set a rowid or if the database does not support > rowids, this attribute should be set to None. > > (I interpret "should" as understood by RFC 2119.)
Well, it may be a little stronger than the SHOULD in the RFC, but then again the whole DB-API is about conventions and if they don't make sense for a database backend, it is possible to deviate from the spec, esp. for optional extensions such as .lastrowid. > So, my follow-up question becomes: > I see no point in reverting to pre Python 3.6 behaviour. I would rather > change the default value to be 0 (to get rid of the dirty flag in GH-30380), > and to make the behaviour more consistent with how the actual SQLite API > behaves. > > > Do you have an opinion about such a change (in behaviour)? Is 0 a valid row ID in SQLite ? If not, then I guess this would be an alternative to None as suggested by the DB-API. If it is a valid row ID, I'd suggest to go back to resetting to None, since otherwise code might get confused: if an UPDATE does not get applied (e.g. a condition is false), code could then still take .lastrowid as referring to the UPDATE and not a previous operation, since code will now know whether the condition was met or not. -- Marc-Andre Lemburg eGenix.com ---------- title: [sqlite3] lastrowid improvements -> [sqlite3] move set lastrowid out of the query loop and enable it for executemany() _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue46249> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
