Add the shape to the model. Django

[Amritpal]

Just started studying Django. There's a uniform. I want one of her fields to get a full meaning and add this value to one of the attributes of the existing model.Product) Here are models:

class Product(models.Model):
    class Meta():
        db_table = 'Product'
idModel = models.ForeignKey(SkiModel)
growth_from = models.IntegerField()
growth_to = models.IntegerField()
weight_from = models.IntegerField()
weight_to = models.IntegerField()
cost = models.IntegerField()
quantity_in_stock = models.IntegerField(default=0)
def __str__(self):
    return str(self.id)

class Delivery(models.Model):

class Meta():

db_table = 'Delivery'
Product = models.ForeignKey(Product)
Amount = models.IntegerField()
Receipt_date = models.DateField()
User = models.ForeignKey(User)

Here's the shape:

class DeliveryForm(ModelForm):

class Meta():

model = Delivery

fields = 'Product', 'Amount', 'Receipt_date'

Here's the function. views.py:

def add_delivery(request, user_id):

if request.POST:

form = DeliveryForm(request.POST)

if form.is_valid():

Delivery = form.save(commit=False)

Delivery.User = User.objects.get(id=user_id)

form.save()

Product.objects.get(id=int(form['Product'].value())).quantity_in_stock += int(form['Amount'].value())

return redirect('/Delivery/')

Not adding. Thank you.

[Kadyn]

Modified records must be recorded:

pr = Product.objects.get(id=int(request.POST.get('Product')))
pr.quantity_in_stock += int(request.POST.get('Amount'))
pr.save()