How to fix add to cart functionality in django? - django

Question

I'm building an ecommerce platform and I want to create the add to cart functionality in the website. But for some reason the Product Id is showing null.
Here's the codes:
models.py
class Products(models.Model):
user = models.ForeignKey(User, on_delete = models.CASCADE)
title = models.CharField(max_length = 255)
product_category = models.CharField(choices = CATEGORY_CHOICES, max_length = 100)
description = models.TextField()
price = models.FloatField(max_length= 5)
class Cart(models.Model):
user = models.ForeignKey(User, on_delete = models.CASCADE)
products = models.ForeignKey(Products, on_delete = models.CASCADE)
views.py
def add_cart(request):
product_id = Products.id
new_product = Cart.objects.get_or_create(id=product_id, user=request.user)
return redirect('/')
templates
<div class="product-wrapper">
<h1 style="font-size:24px">{{product.title}}</h1>
<div class="product-price">
<p style="text-decoration-line:line-through;">$ {{product.price}}</p>
<a href="{% url 'add-product' product.product_id %}">Add to cart<a>
</div>
When I try to click this link it gives me this error: Field 'id' expected a number but got <django.db.models.query_utils.DeferredAttribute object at 0x000002468A4F8550>.
Any suggestion will be really helpful. Thank you

Answer 1

Finally, I've fixed this.
view.py
def add_to_cart(request, slug):
products = Products.objects.get(slug=slug)
ncart = Cart.objects.create(user=request.user, products=products)
ncart.save()
return redirect('/')
template
<div class="product-wrapper">
<h1 style="font-size:24px">{{product.title}}</h1>
<div class="product-price">
<p style="text-decoration-line:line-through;">$ {{product.price}}</p>
<a href="{% url 'add-to-cart' product.slug %}">Add to cart<a>
</div>
urls.py
path('cart/add/<slug:slug>', views.add_to_cart, name = 'add-to-cart')

Answer 2

Considering you've got Products instance already, in that case
Query directly like:
new_product = Cart.objects.get_or_create(products=Products)
If you want to query from the product_id, do it like that:
product_id = Products.pk
new_product = Cart.objects.get_or_create(products_id=product_id)
In addition:
request.user contains a dictionary, you can't pass it directly to query. And the user field has name buyer, so change that query like that:
product_id = Products.pk
new_product = Cart.objects.get_or_create(products=Products, buyer_id=request.user['pk'])