What to return to django admin if user has not username or something else

Question

In short i am doing online store and in django admin i display authenticated users 'username' but there are users which didn't authenticated

So if authenticated users will order something it's okay i have their data. But if unauthenticated users will order? What to show in django admin? If i will request from user only his name from this no result. Because we know django need full authorization

models.py

class Cart(models.Model):
    user = models.ForeignKey(User, null=True, blank=True)
    products = models.ManyToManyField(Product, through=CartProduct)

    class Meta:
        verbose_name = 'Cart'
        verbose_name_plural = 'Cart'

    def __str__(self):
        return self.user.username # That for authenticated users

views.py

class CartView(View):

    def get(self,request,*args,**kwargs):
        cart_id = request.session.get('cart_id')
        if cart_id == None:
            cart = Cart()
            cart.save()
            request.session['cart_id'] = cart_id

        cart = Cart.objects.get(id=cart_id)
        product_id = request.GET.get('product')
        delete_product = request.GET.get('delete')
        if product_id:
            product_instance = get_object_or_404(Product, id=product_id)
            amount = request.GET.get('amount')
            cart_product = CartProduct.objects.get_or_create(cart=cart, product=product_instance)[0]

            if delete_product:
                cart_product.delete()
            else:
                cart_product.amount = amount
                cart_product.save()
        return HttpResponseRedirect('/')

Answer 1

You could use IP adress, but that could be confusing / multiple people could share one.

So my suggestion would be to use Django's built-in session framework.

Pulling from this stackoverflow answer, you'll see that you can gather the current session key from the request object.

Then it's just a matter of changing your Cart model :

from django.contrib.sessions.models import Session

class Cart(models.Model):
    user = models.ForeignKey(User, null=True, blank=True)
    session = models.ForeignKey(Session, null=True, blank=True)
    products = models.ManyToManyField(Product, through=CartProduct)

    class Meta:
        verbose_name = 'Cart'
        verbose_name_plural = 'Cart'

    def __str__(self):
        if self.user :
             return self.user.username # For for authenticated users
        else if self.session :
             return self.session.session_key
        else :
             return "Anonymous"

And of course, you'll need to make sure that you add the request.session to your Cart object when you create it.

Finally, it seems the session object can still be empty sometimes, so you should look at force-saving it if you really don't want an "Anonymous" line in your admin. This answer makes force-saving the session quite simple :

if not request.session.session_key:
    request.session.save()
session_id = request.session.session_key

Answer 2

Write a dispatch method inside the class so that you can check wether the user is authenticated request.user.is_authenticated will return the status of user authentication. If the user is not authenticated then save the user as your need