[Answer]-Override save vs Custom field in Django

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How about using the following structure:

class MyModel(models.Model):
    A_Field=models.IntegerField()
    B_Field=models.IntegerField()
    C_Field=models.IntegerField(null=True, blank=True)#this is the generated field

    def get_C(self):
        return self.A_Field+self.B_Field

    def save(self, force_insert=False, force_update=False):
        self.C_Field=self.get_C()
        super(MyModel, self).save(force_insert, force_update)

Assigning an already correct default value (e.g. default = get_C in the field definition) will fail as A_Field and B_Field will not have a value at the point it is invoked.If you need this to be immediately evaluated as soon as you change A and B in a form you will need to use JS to do this.

👤ger.s.brett

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