模板渲染期间出错：/products/product-3/ 处的 NoReverseMatch

Question

您能帮我理解以下错误吗？ 我正在学习 Django，并且确实坚持使用视图的反向渲染。 当我点击产品链接时，它应该会转到产品页面，但会抛出错误。

我的分析 我在产品单一功能中插入了打印语句，并且可以在终端中看到该程序可以正常工作，直到它渲染视图，这有帮助吗？

从终端

15/Nov/2020 22:49:59] "GET /products/ HTTP/1.1" 200 7582
<WSGIRequest: GET '/products/product-3/'>
{'product': <Product: Product 3>, 'images': <QuerySet []>}
products/single.html
Internal Server Error: /products/product-3/
Traceback (most recent call last):

错误 /products/product-3/ 处的 NoReverseMatch 找不到“add_to_cart”的反向。 'add_to_cart' 不是有效的视图函数或模式名称。 请求方法：GET 请求网址：http://127.0.0.1:8000/products/product-3/ Django 版本：3.1.3 异常类型：NoReverseMatch 异常值：
找不到“add_to_cart”的反向。 'add_to_cart' 不是有效的视图函数或模式名称。

HTML

{% extends "base.html" %} {% block content %}
<h1>Search for {{ query }}</h1>
{{ product }}

<table class="table">
  <thead>
    <th></th>
    <th>Product</th>
  </thead>
  <tbody>
    {% for product in product_htm %}
    <tr>
      <td>Image</td>
      <td><a href="{ product.get_absolute_url }}"> {{ product }}</a></td>
    </tr>
    {% endfor %}
  </tbody>
</table>
{% endblock %}

产品应用中的models.py

# Create your models here.
class Product(models.Model):
    def get_absolute_url(self):
        return reverse("product_app:single_product", kwargs={"slug": self.slug})

products views.py

def single(request, slug):
    product = Product.objects.get(slug=slug)
    images = ProductImage.objects.filter(product=product)
    context = {'product': product, 'images': images}
    template = 'products/single.html'
    print(request)
    print(context)
    print(template)
    return render(request, template, context)

产品应用 urls.py 从 。导入视图

app_name = 'product_app'

urlpatterns = [
    path('', views.index, name='home'),
    path('s/', views.search),
    path('products/', views.all, name='products'),
    path('products/<slug:slug>/', views.single, name='single_product'),
]

购物车 urls.py

from . import views
# import (index, ProductSingleView)

app_name = 'cart_app'

extra_patterns = [
    path('cart/carts/<slug:slug>/', views.add_to_cart),
]
urlpatterns = [
    path('cart/', include(extra_patterns), name='add_to_cart'),
    path('cart/<int:id>', views.remove_from_cart, name='remove_from_cart'),
    path('', views.view, name='cart'),
]

carts views.py

# Create your views here.
from products.models import Product, Variation
from .models import Cart, CartItem


def view(request):
    try:
        the_id = request.session['cart_id']
    except DoesNotExist:
        the_id = None
    if the_id:
        cart = Cart.objects.get(id=the_id)
        new_total = 0.00
        for item in cart.cartitem_set.all():
            line_total = float(item.product.price) * item.quantity
            new_total += line_total

        request.session['items_total'] = cart.cartitem_set.count()
        cart.total = new_total
        cart.save()
        
        context = {"cart": cart}
    else:
        empty_message = "Yout cart is empty, please keep shopping"
        context = {"empty": True, "empty_message": empty_message}

    template = "cart/view.html"
    return render(request, template, context)

def remove_from_cart(request, id):
    try:
        the_id = request.session['cart_id']
        cart = Cart.objects.get(id=the_id)
    except:
        return HttpResponseRedirect(reverse('cart_app:cart'))

    cartitem = CartItem.objects.get(id=id)
    cartitem.cart = None
    cartitem.save()
    return HttpResponseRedirect(reverse('cart_app:cart'))

def add_to_cart(request, slug):
    request.session.set_expiry(120)

    try:
        the_id = request.session['cart_id']
    except:
        new_cart = Cart()
        new_cart.save()
        request.session['cart_id'] = new_cart.id
        the_id = new_cart.id

    cart = Cart.objects.filter(id=the_id)

    try:
        product = Product.objects.get(slug=slug)
    except Product.DoesNotExist:
        print("except1")

    product_var = []
    if request.method == "POST":
        qty = request.POST['qty']
        for item in request.POST:
            key = item
            val = request.POST[key]
            try:
                v = Variation.objects.get(product=product, category__iexact=key, title__iexact=val)
                product_var.append(v)
            except Variation.DoesNotExist:
                pass

        cart_item = CartItem.objects.create(cart=cart, product=product)
        print("iam here")
        if len(product_var) > 0:
            # * adds each item
            cart_item.variations.add(*product_var)
        cart_item.quantity = qty
        cart_item.save()


        return HttpResponseRedirect(reverse('cart_app:cart'))
    else:
        return HttpResponseRedirect(reverse('cart_app:cart'))

项目电子商务中的urls.py

from django.contrib import admin
from django.urls import path, include
from django.conf import settings
from django.conf.urls.static import static

urlpatterns = [
    path('', include('products.urls')),
    path('cart/', include('carts.urls'), name='cart'),
    path('admin/', admin.site.urls),
]

Answer 1

在您的 url_patterns 中，包含 name='add_to_cart' 的行包含在其中。把那个名字拿出来放在extra_patterns 中。我认为您正在尝试命名可能包含多个项目的包含。

from . import views
# import (index, ProductSingleView)

app_name = 'cart_app'

extra_patterns = [
    path('cart/carts/<slug:slug>/', views.add_to_cart, name='add_to_cart'),
]
urlpatterns = [
    path('cart/', include(extra_patterns)),
    path('cart/<int:id>', views.remove_from_cart, name='remove_from_cart'),
    path('', views.view, name='cart'),
]

Answer 2

我首先看到的是您的 html 文件中有错字。你只有一个左大括号

product.get_absolute_url

另外，当您调用 get_absolute_url 时，它会返回

reverse("product_app:single_product", kwargs={"slug": self.slug})

确保产品确实有self.slug，因为我无法判断您的models.py 中的产品类是否有任何字段。

如果有帮助，请告诉我，我很乐意提供帮助。