On Sep 6, 9:02 am, Mike Dewhirst <mi...@dewhirst.com.au> wrote: > On 6/09/2010 4:19pm, kmpm wrote: > > > I have a project running in a manufacturing industry that is actually > > built upon django. > > In this I need to generate a unique serial, batch or lot number > > (depending on what you would like to call it) that is a running number > > from 0 to whathever for each and every day. > > So when every day ticks over at midnight, the serial number starts at > zero again? Does production continue across the time 00:00? Why don't > you use a continuously increment number? > > I don't know what the "right" thing to do is. I'm sure there will be a > classic solution. I think I would be writing a singleton function > nextnum() which returns the next number as required and then > > lot_no = models.IntegerField(default=nextnum) > > I'm not sure what would happen threadwise but a singleton would be a > natural place to deal with thread-locking and restarting the sequence > when the clock ticks over. > > lot_no then gets the value prior to the save() > > Mike
Yes it ticks over at midnight, and no there is no production at that time. More or less office hours only. A singleton would be nice but as you said it's not thread safe and won't scale nicely if we were to use multiple frontend servers or anything like that. There is a project called django-idmapper[1] that I just found that might solve it by using a model that seems to be stored in shared memory. If running on multiple frontends that would need to be something like memcached but I don't know about thread safety and concurrency there either. [1]http://github.com/dcramer/django-idmapper -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-us...@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.
