
from django.shortcuts import render, redirect

from products.models import Product
from .models import Cart

def cart_home(request):
    cart_obj, new_obj  = Cart.objects.new_or_get(request)
    return render(request, "carts/home.html", {"cart": cart_obj})

def cart_update(request):
    print(request.POST)
    product_id = request.POST.get('product_id')
    if product_id is not None:
        try:
            product_obj = Product.objects.get(id = product_id)
        except Product.DoesNotExist:
            print("Mostrar mensagem ao usuário, esse produto acabou!")
            return redirect("cart:home")
        cart_obj, new_obj = Cart.objects.new_or_get(request) 
        if product_obj in cart_obj.products.all(): 
            cart_obj.products.remove(product_obj) 
        else: 
            cart_obj.products.add(product_obj)
    return redirect("cart:home")

Acesse

django_ecommerce/carts/templates/carts/home.html


{% extends "base.html" %}
{% block content %}
  <h1>Carrinho</h1>
  {% if cart.products.exists %}
    <table class="table">
      <thead>
        <tr>
          <th>#</th>
          <th>Nome do produto</th>
          <th>Preço do produto</th>
        </tr>
      </thead>
      <tbody>
        {% for product in cart.products.all %}
        <tr>
          <thscope="row">{{ forloop.counter }}</th>
          <td><a href='{{ product.get_absolute_url }}'>{{ product.title }}</a><small><a href='#'>Deseja remover?</a></small></td>
          <td>{{ product.price }}</td>
        </tr>
        {% endfor %}
        <tr>
          <tdcolspan="2"></td>
          <td><b>Subtotal</b> {{ cart.subtotal }}</td>
        </tr>
        <tr>
          <tdcolspan="2"></td>
          <td><b>Total</b> {{ cart.total }}</td>
        </tr>
      </tbody>
    </table>
  {% else %}
    <p class='lead'>Carrinho vazio</p>
  {% endif %}
{% endblock %}