Django change field value in queryset

Question

#models.py

class Product(models.Model):
    price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, default=0.0000)
    discount = models.DecimalField(max_digits=10, decimal_places=2, blank=True, default=0.0000)
    is_discount = models.BooleanField(default=False)

#views.py

def page(request):
    product = Product.objects.get(pk=1)

I have main product price, sometime I need to enable discount price, so if I enabled it in "is_discount" and when I make product instance at result I need to get by product.price the value from "discount".

I understand that I can make it with

price = product.price
if product.is_discount:
    price = product.discount

but this solution is not good for me.

Answer 1

Consider using a calculated field ( property ):

class Product(models.Model):
    price = models.DecimalField(max_digits=10, decimal_places=2, blank=True, default=0.0000)
    discount = models.DecimalField(max_digits=10, decimal_places=2, blank=True, default=0.0000)
    is_discount = models.BooleanField(default=False)
    
    @property
    def current_price(self):
        return self.discount if self.is_discount else self.price

Product.objects.get(pk=1).current_price