Rutnet:

I am working on a Django Cart application. I have two models Cart and Item. I am trying to get the quantity to update when an Item is added to the basket but cant get the views to work properly. I am having problems getting item_obj assignment to work - do I need to do anything with the model manager here? Any help is really appreciated.

Models.py

class Cart(models.Model):
    user = models.ForeignKey(User, null=True, blank=True)
    products = models.ManyToManyField(Product, blank=True)
    total = models.DecimalField(default=0.00, max_digits=10, decimal_places=2)
    updated = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(auto_now_add=True)

    objects = CartManager()

    def __str__(self):
        return str(self.id)

class Item(models.Model):
    item = models.ForeignKey(Product, null=True)
    cart = models.ForeignKey(Cart, null=True)
    quantity = models.PositiveIntegerField()

Views.py extract

def cart_update(request):
    product_id = request.POST.get('product_id')
    product_obj = Item.objects.get(id=product_id)
    print(item_id)
    item_obj = Item.objects.get(id=product_id)
    cart_obj, new_obj = Cart.objects.new_or_get(request)
    if item_obj in cart_obj.products.all():
        cart_obj.products.add(product_obj)
        item_obj.quantity += 1
        item_obj.save()
    else:
        cart_obj.products.add(product_obj)
    return redirect("cart:home")