How to set field values dynamically based on other fields in django-CodePudding

I have two models in Django.

class Product(models.Model):
    description = models.CharField('Description', max_length=200)
    price = models.FloatField()

class Sell(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    price = models.FloatField()  

    def save(self, *args, **kwargs):
        self.price = self.product.price
        super(Sell, self).save(*args, **kwargs)

I want to copy dynamically Product.price value to Sell.price and set it as a default value. User can change Sell.price value later. I have implemented save() method for this purpose, but it is not showing any value. How to do it?

CodePudding user response：

Yes, your approch is fine just need to change price = models.FloatField(blank=True,null=True) like this

models.py

class Product(models.Model):
    description = models.CharField('Description', max_length=200)
    price = models.FloatField()

    def __str__(self):
        return self.description

class Sell(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    price = models.FloatField(blank=True,null=True)  

    def save(self, *args, **kwargs):
        self.price = self.product.price
        super(Sell, self).save(*args, **kwargs)

models.py

Admin Panel Output