On 8/18/07, Doug B <[EMAIL PROTECTED]> wrote: > > > [PYTHON] > > class Order(models.Model): > > def count_items(self): > > items = 0 > > for item in self.orderitem_set.filter(order=self): > > items += item.quantity > > return items > > count = property(count_items) > > [/PYTHON] > > > For the instance.othermodel_set objects, the 'order=self' is already > implied, you shouldn't supply it as a filter argument. I have a > feeling the error is from specifying the same column twice. Try > self.orderitem_set.all(). > I tried that, but I get the same error, the traceback displays that line as the "buggy" one: for item in self.orderitem_set.all():
> You might also consider dropping to sql for stuff like this if you've > got performance issues. Probably overkill here, but since I had to > spend some time figuring it out on a similar problem today, maybe it > will help you. > from django.db import connection > c=connection.cursor() > q="select SUM(quantity) as item_count from %s where order=%s" % > (self.orderitem_set.model._meta.db_table,self._get_pk_val()) > c.execute(q) > count = c.fetchone()[0] # grab the first and only row > Thanks for the tip. I did something like that but then found a snippet [0] doing what I wanted in a more django-like way. I still don't know if use my own sql sentences for this cases or stick to the django api. I guess it's a decision based on performance, the problem is that I don't know which is more performant. Each cart won't have many items, so I guess counting them is not going to be a demanding process, right? AlvAro "You can't change the world, but you can change your mind." Software Libre: El conocimiento no puede tener dueño. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
