Create a field whose value is a calculation of other fields' values

django, python

Solution

Justin Hamades answer

class PO(models.Model)
    qty = models.IntegerField(null=True)
    cost = models.IntegerField(null=True)

    @property
    def total(self):
        return self.qty * self.cost

Problem

``` class PO(models.Model) qty = models.IntegerField(null=True) cost = models.IntegerField(null=True) total = qty * cost ``` How will I solve `total = qty * cost` above. I know it will cause an error, but have no idea of how to deal with this.

Original source

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