Python: if more than one of three things is true, return false

Question

I\'m writing a django model that allows my site to have coupons.

Coupons can have three types: lifetime account voucher, certain period of months voucher, certain numb

Answer 1

You could also use a list comp to filter false values:

if len([x for x in [self.months, self.dollars, self.lifetime] if x]) > 1:
    raise ValueError()

Or building off MRAB's answer:

if sum(map(bool, [self.months, self.dollars, self.lifetime])) > 1:
    raise ValueErrro()