Thank you, I also believe it is Race condition. I do not want to use get_or_create as I like to have control over DB writes and updates. I will try Unique_together and catch the integrity error exception as Kurtis suggested or check again before doing save().
or just thinking aloud, Is there a way to acquire a lock which can serialize any other requests which have same "a" and "b" values? On Friday, June 22, 2012 7:52:49 AM UTC-7, Daniel Roseman wrote: > > On Friday, 22 June 2012 06:23:32 UTC+1, ydjango wrote: >> >> I have code as >> >> view_a(request): >> .... Populate my_a, my_b and my_c... >> try: >> tp = TP.objects.get(a__exact = my_a, b__exact = my_b) >> except TP.DoesNotExist, e: >> tp = TP() >> tp.a = my_a >> tp.b = my_b >> tp.c = my_c >> tp.save() >> else: >> tp.c = my_c >> tp.save() >> >> This view is called by ajax calls. TP is a django model and mysql db. >> I am using django 1.1.4/ python2.5/mod_wsgi2.5, >> >> I find that in, one case, two rows with same value of a and b has been >> created in DB. ( value of c was different) >> What could have caused it? >> >> Any clues or hints on how to track down this problem or what to look for >> will be appreciated. >> >> > You probably have a race condition. You should use the built-in > `get_or_create` manager method, which helps to minimize that sort of thing > (it's not perfect, but it's better than coding it yourself). > -- > DR. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To view this discussion on the web visit https://groups.google.com/d/msg/django-users/-/6XYOOu3cmIoJ. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
