ok i understood thanks for help On Sunday, April 7, 2019 at 11:58:50 AM UTC+2, Roger Gammans wrote: > > Omar, > > When posting question to the list it's good practice to practice tell us a > little bit about what your trying to do, and how what > actions cause the error to occur. > > In this case though you only have a (single line in CalcPoints) which uses > the '*' operator. > > On Sat, 2019-04-06 at 10:35 -0700, omar ahmed wrote: > > models.py > def CalcPoints(self): > return self.won*3 + self.draw > > > > The python documentation has this to say about the '*' operator > *(from: * > https://docs.python.org/3/reference/expressions.html#binary-arithmetic-operations > ) > > *The * (multiplication) operator yields the product of its arguments. The > arguments must either both be numbers, or one argument must be an integer > and the other must be a sequence. In the former case, the numbers are > converted to a common type and then multiplied together. In the latter > case, sequence repetition is performed; a negative repetition factor yields > an empty sequence.* > > Since you've provided a literal integer ( the '3') as one of your > arguments, we can deduce the None value > is in self.won. Since you have 'declared' self.won as an IntegerField; we > can see that as in the > normal case we should satisfy the first clause of the reference, "*arguments > must either both be numbers"* > however so some reason self.won is None in your case. > > Without seeing the rest of your code it's impossible to guess accurately > but my instinct is your haven't > initialised your instance from the database (or set a won value when > creating the object). > > If you expected to have a default value you need to set one where you set > up self.won see > : https://docs.djangoproject.com/en/2.2/ref/models/fields/#default > > HTH, > > -- > > Roger Gammans <[email protected] <javascript:>> > >
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