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

I don't know if this is better for you, but doing it this way would work:

if (self.months && self.dollars) || (self.months && self.lifetime) || (self.dollars && self.lifetime):
   raise ValueError("Coupon can be valid for only one of: months, lifetime, or dollars")