我正在使用django 2.2.5创建一个电子商务站点。我一直在关注udemy上的教程，其中讲师的步调很快，而他使用的是django的旧版本，我一直在试图暂停以确保我的代码正确（这是AWFUL）。我现在正在创建一个购物车。价格正在正确更新，但未显示产品价格和说明。我回头检查了导致该项目这一部分的所有视频，但我似乎找不到我做错的事情，所以我决定来这里看第二眼/第三眼能够查看为什么不显示产品价格和说明。
购物车（cart.html）：我有一个forloop.counter，它遍历产品，并假定显示添加到购物车中的产品的价格和说明。
{% extends 'base.html' %}
{% block content %}
{% load staticfiles %}
<div class="pb-5">
<div class="container">
<div class="row">
<div class="col-lg-12 p-5 bg-white rounded shadow-sm mb-5">
<!-- Shopping cart table -->
<div class="table-responsive">
{% if cart.product.exists %}
<table class="table">
<thead>
<tr>
<th scope="col" class="border-0 bg-light">
<div class="p-2 px-3 text-uppercase">Product</div>
</th>
<th scope="col" class="border-0 bg-light">
<div class="py-2 text-uppercase">Price</div>
</th>
<th scope="col" class="border-0 bg-light">
<div class="py-2 text-uppercase">Quantity</div>
</th>
<th scope="col" class="border-0 bg-light">
<div class="py-2 text-uppercase">Remove</div>
</th>
</tr>
</thead>
<tbody>
{% for product in cart.products.all %}
<tr>
<th scope="row" class="border-0">{{ forloop.counter }}
<div class="p-2">
<img src="{{product.image}}" alt="" width="70" class="img-fluid rounded shadow-sm">
<div class="ml-3 d-inline-block align-middle">
<h5 class="mb-0"> <a href="{{ product.get_absolute_url }}" class="text-dark d-inline-block align-middle">{{ product.name }}</a></h5><span class="text-muted font-weight-normal font-italic d-block">Category: Watches</span>
</div>
</div>
</th>
<td class="border-0 align-middle"><strong>{{product.price}}</strong></td>
<td class="border-0 align-middle"><strong>3</strong></td>
<td class="border-0 align-middle"><a href="#" class="text-dark"><i class="fa fa-trash"></i></a></td>
</tr>
{% endfor %}
</tbody>
</table>
</div>
{% else %}
<p class="lead">Cart is empty</p>
{% endif %}
<!-- End -->
</div>
</div>
<div class="row py-5 p-4 bg-white rounded shadow-sm">
<div class="col-lg-6">
<div class="bg-light rounded-pill px-4 py-3 text-uppercase font-weight-bold">Coupon code</div>
<div class="p-4">
<p class="font-italic mb-4">If you have a coupon code, please enter it in the box below</p>
<div class="input-group mb-4 border rounded-pill p-2">
<input type="text" placeholder="Apply coupon" aria-describedby="button-addon3" class="form-control border-0">
<div class="input-group-append border-0">
<button id="button-addon3" type="button" class="btn btn-dark px-4 rounded-pill"><i class="fa fa-gift mr-2"></i>Apply coupon</button>
</div>
</div>
</div>
<div class="bg-light rounded-pill px-4 py-3 text-uppercase font-weight-bold">Instructions for seller</div>
<div class="p-4">
<p class="font-italic mb-4">If you have some information for the seller you can leave them in the box below</p>
<textarea name="" cols="30" rows="2" class="form-control"></textarea>
</div>
</div>
<div class="col-lg-6">
<div class="bg-light rounded-pill px-4 py-3 text-uppercase font-weight-bold">Order summary </div>
<div class="p-4">
<p class="font-italic mb-4">Shipping and additional costs are calculated based on values you have entered.</p>
<ul class="list-unstyled mb-4">
<li class="d-flex justify-content-between py-3 border-bottom"><strong class="text-muted">Order Subtotal </strong><strong>{{ cart.subtotal }}</strong></li>
<li class="d-flex justify-content-between py-3 border-bottom"><strong class="text-muted">Shipping and handling</strong><strong>$10.00</strong></li>
<li class="d-flex justify-content-between py-3 border-bottom"><strong class="text-muted">Tax</strong><strong>$0.00</strong></li>
<li class="d-flex justify-content-between py-3 border-bottom"><strong class="text-muted">Total</strong>
<h5 class="font-weight-bold">{{ cart.total }}</h5>
</li>
</ul><a href="#" class="btn btn-dark rounded-pill py-2 btn-block">Procceed to checkout</a>
</div>
</div>
</div>
</div>
</div>
</div>
{% endblock %}
购物车（cart / models.py）：
from django.conf import settings
from django.db import models
from django.db.models.signals import pre_save, post_save, m2m_changed
from products.models import Product
User = settings.AUTH_USER_MODEL
class CartManager(models.Manager):
def new_or_get(self, request):
cart_id = request.session.get("cart_id", None)
qs = self.get_queryset().filter(id=cart_id)
if qs.count() == 1:
new_obj = False
cart_obj = qs.first()
if request.user.is_authenticated and cart_obj.user is None:
cart_obj.user = request.user
cart_obj.save()
else:
cart_obj = Cart.objects.new(user=request.user)
new_obj = True
request.session['cart_id'] = cart_obj.id
return cart_obj, new_obj
def new(self, user=None):
user_obj = None
if user is not None:
if user.is_authenticated:
user_obj = user
return self.model.objects.create(user=user_obj)
class Cart(models.Model):
user = models.ForeignKey(User, null=True, blank=True, on_delete=True)
products = models.ManyToManyField(Product, blank=True)
subtotal = models.DecimalField(default=0.00, max_digits=19, decimal_places=2)
total = models.DecimalField(default=0.00, max_digits=19, decimal_places=2)
updated = models.DateTimeField(auto_now_add=True)
timestamp = models.DateTimeField(auto_now_add=True)
objects = CartManager()
def __str__(self):
return str(self.id)
def m2m_changed_cart_receiver(sender, instance, action, *args, **kwargs):
if action == 'post_add' or action == 'post_remove' or action == 'post_clear':
products = instance.products.all()
total = 0
for x in products:
total += x.price
if instance.subtotal != total:
instance.subtotal = total
instance.save()
m2m_changed.connect(m2m_changed_cart_receiver, sender=Cart.products.through)
def pre_save_cart_receiver(sender, instance, *args, **kwargs):
if instance.subtotal > 0:
instance.total = instance.subtotal + 6
else:
instance.total = 0.00
pre_save.connect(pre_save_cart_receiver, sender=Cart)
（购物车/views.py）：
from django.shortcuts import render, redirect
from products.models import Product
from .models import Cart
def cart_home(request):
template = "carts/cart.html",
cart_obj, new_obj = Cart.objects.new_or_get(request)
return render(request, template, {"cart": cart_obj})
def cart_update(request):
product_id = request.POST.get('product_id')
if product_id is not None:
product_obj = Product.objects.get(id=product_id)
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")
产品视图（products / views.py）：
class ProductDetailSlugView(DetailView):
queryset = Product.objects.all()
template_name = "products/detail.html"
def get_context_data(self, *args, **kwargs):
context = super(ProductDetailSlugView, self).get_context_data(*args, **kwargs)
cart_obj, new_obj = Cart.objects.new_or_get(self.request)
context['cart'] = cart_obj
return context
def get_object(self, *args, **kwargs):
request = self.request
slug = self.kwargs.get('slug')
try:
instance = Product.objects.get(slug=slug)
except Product.DoesNotExist:
raise Http404("Not Found")
except Product.MultipleObjectsReturned:
qs = Product.objects.filter(slug=slug)
instance = qs.first()
except:
raise Http404("hmmm can't seem to find product")
return instance
答案 0 :(得分：0)
在我更改的cart.html中
{％，如果cart.product.exists％}
到
{％，如果cart.products.exists％}