What are F() expressions and where are they documented ? (just didn't hear the term until now)
About your win_percentage column , wouldn't you rather have it as a method which is being calculated from the columns wins and losses instead of a column stored inside the table ? On Sep 15, 8:36 pm, Brent Hagany <brent.hag...@gmail.com> wrote: > I'm having some trouble getting F() expressions to obey my parentheses > when I don't want the default order of operations. For example, given > the model: > > class MyModel(models.Model): > wins = models.DecimalField(max_digits=1, decimal_places=0) > losses = models.DecimalField(max_digits=1, decimal_places=0) > win_percentage = models.DecimalField(max_digits=4, > decimal_places=3, default=Decimal('0.000')) > > I get the following results when trying to calculate the > win_percentage: > > In [1]: MyModel.objects.create(wins=2, losses=4) > Out[1]: <MyModel: MyModel object> > > In [2]: MyModel.objects.all().update(win_percentage=F('wins') / (F > ('wins') + F('losses'))) > Out[2]: 1 > > # I expect this to return Decimal("0.333") > In [3]: MyModel.objects.get(pk=1).win_percentage > Out[3]: Decimal("5.000") > > It appears to be ignoring the parentheses around F('wins') + F > ('losses'), and so instead of 2 / (2 + 4) = .333, I'm getting 2 / 2 + > 4 = 5. Am I doing this wrong, or is this by design, or is it a bug? --~--~---------~--~----~------------~-------~--~----~ 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 django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---