如何在Django管理模型中计算字段

Question

i have a model that i have added to my django admin panel

from django.db import models
from django.contrib import admin

class Employee(models.Model):
   fee = models.IntegerField(null=False)
   vat = models.IntegerField(null=False)

and have added this my admin panel

admin.site.register(Employee, EmployeeAdmin)
 readonly_fields('vat',)

so while adding a new employee, the admin inputs the fee amount, id like vat to be calculated and shown as a direct result of entering the vat. how can create this calculation on the fly as the admin is entering the fee

Answer 1

i might be completely wrong here, but couldn't you just use a property for that instead of storing vat in the database?

on your model, declare:

@property
def vat(self):
    return calculation_of_vat(self.fee)

Answer 2

you can override the save method:

def save(self, *args, **kwargs):
    self.vat=self.calculate_vat(self.fee)
    super(ClassModel, self).save(*args, **kwargs)