cart - Django - TypeError - Field 'id' expected a number but got <WSGIRequest: GET '/marketplace/add_to_cart/5/'>

Question

I'm pretty new to Django and face a problem trying to implement a cart for my e-shopping website. As I call my "add_to_cart" function, I want to be sure if either a cart exists for this session, and if there is already a reference for the selected item in this cart.

Here is my models.py :

CART_ID = 'CART-ID'

class Cart(models.Model):
        creation_datetime       = models.DateTimeField(auto_now_add=True)
        update_datetime         = models.DateTimeField(auto_now=True)
        checked_out             = models.BooleanField(default=False)
        user                    = models.ForeignKey(User,on_delete=models.DO_NOTHING, null=True, blank=True)

        @classmethod
        def create(cls):
                cart_id = request.session.get(CART_ID)
                if cart_id:
                        cart = models.Cart.objects.filter(id=cart_id, checked_out=False).first()
                        if cart is None:
                                cart = cls()
                                request.session[CART_ID] = cart.id
                else:
                        cart = cls()
                        request.session[CART_ID] = cart.id
                return cart

        def add(self, article, prix_unitaire, quantite=1):
                item = Item.objects.filter(cart_id=self.id, article=article).first()
                if item:
                        item.prix_unitaire = prix_unitaire
                        item.quantite += int(quantite)
                        item.save()
                else:
                        Item.objects.create(cart_id=self.id, article=article, prix_unitaire=prix_unitaire, quantite=quantite)

class Item(models.Model):
        cart            = models.ForeignKey(Cart, on_delete=models.CASCADE)
        article         = models.ForeignKey(Article, on_delete=models.CASCADE)
        quantite        = models.PositiveIntegerField()
        prix_unitaire   = models.PositiveIntegerField()

        def prix_total(self):
                return self.quantite * self.prix_unitaire
                prix_total = property(prix_total)

in my views.py, I defined my "add_to_cart" function :

def add_to_cart(request, pk, quantite=1):
        article = Article.objects.get(pk=pk)
        cart    = Cart(request)
        cart.add(article, article.prix_unitaire, quantite)

and my urls.py

urlpatterns = [
...
        path('add_to_cart/<int:pk>/', add_to_cart, name='add_to_cart'),

As I call the function, I get this error :

TypeError at /marketplace/add_to_cart/5/
Field 'id' expected a number but got <WSGIRequest: GET '/marketplace/add_to_cart/5/'>.

In the stack, I have this highlighted :

/home/max/elien_dev/ELIEN_MARKETPLACE/models.py, line 85, in add
        item = Item.objects.filter(cart_id=self.id, article=article).first() …
▼ Local vars
Variable        Value
article         <Article: Article object (5)>
prix_unitaire   400
quantite        1
self            <Cart: Cart object (<WSGIRequest: GET '/marketplace/add_to_cart/5/'>)>

It seems that I'm not referencing my cart as I should as I try to check if the item is already in the cart. Tried with "cart=self" and other stuff, but I think I'm missing a deeper point here. Any idea ?

Thanks anyway for reading this !

Answer 1

等待大神答复