Friday, August 14, 2015¶
How to log every database change¶
There was an error message on a production server in Eupen:
IntegrityError: (1451, ‘Cannot delete or update a parent row: a foreign key constraint fails (dbname.`contacts_person`, CONSTRAINT city_id_refs_id_d349fc28 FOREIGN KEY (city_id) REFERENCES countries_place (id))’)
The users reported that it happened after asking Lino to delete a countries.Place for which there were no more addresses.
The Apache log confirms this:
126.96.36.199 - username [13/Aug/2015:10:44:46 +0200] "GET /callbacks/8747748654413/yes?_dc=1439455593571 HTTP/1.1" 500 540 "http://lino.local/" "Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Firefox/38.0 Iceweasel/38.1.0"
So it seems that Lino (
lino.core.ddh) failed to see a
contacts.Person object pointing to this countries.Place, and
therefore did not refuse to delete it. And when actually asking MySQL
to delete it, MySQL discovered that person and (correctly) refused to
delete the place.
Otto pointed out that Lino should have an easy way to temporarily log all database changes to a log file. And I must admit that it is currently rather hard to read the logs and to make sure that you didn’t miss something. It would be nice to see each (modifing) request in Lino’s log file. #419 should be trivial…
… so I added a new option
log_each_action_request. And saw that hic
sunt dracones, e.g. Exception: You cannot access body after reading
from request’s data stream. And after implementing it and trying it
in a few situations, I noticed that it is far from logging every
change, and that I should maybe rather move some of the code from
lino.modlib.changes to somewhere below
then extend it so that the
watch_changes() function accepts an
option which specifies where the change should be logged (currently
either in changes.Change or in system.log, but maybe more handlers
in the future). I left the
log_each_action_request there because I am not
Release notes and fixes¶
Ahaa, I got an enlightment: in Lino Noi I must replace the
Ticket.fixed_for field by a new model
lino.modlib.tickets.models.Deployment. One ticket can be
fixed on more than one site at different moments. Lino Noi does
site-specific release notes.