Django 3.1 No reverse match at / not a registered namespace 錯誤

Question

我正在遵循django中關於在線商店設計的舊指南，我在我的一個應用程序 model 文件中使用反向 function 時遇到了一個奇怪的問題。 這是我項目的總體結構：

shop(main project)
 |-myshop(preview of general website pages)
 |-utility(some utilities and context processors)
 |-catalog(catalog related modules of the website)
 |-cart(shopping cart module)
 |-manage.py
 |-db.sqlite3

這些是我的項目的錯誤相關文件：main urls.py

from django.contrib import admin
from django.urls import path, include
from myshop import views

urlpatterns = [
    path('admin/', admin.site.urls),
    path('', views.home_view),
    path('signup/', views.signup_view, name="signup"),
    path('sent/', views.activation_sent_view, name="activation_sent"),
    path('activate/<slug:uidb64>/<slug:token>/', views.activate, name='activate'),
    path('signin/', views.signin_view, name="signin"),
    path('logout/', views.logout_view, name="logout"),
    path('catalog/', include(('catalog.urls', 'catalog'), namespace='catalog')),
]

目錄urls.py ：

from django.urls import path, re_path
from catalog import views

app_name = 'catalog'

urlpatterns = [
   re_path(r'^$', views.home_view, name='catalog_home'),   
   re_path(r'^category/(?P<category_slug>[-\w]+)/$', views.show_category, name='catalog_category'),    
   re_path(r'^product/(?P<product_slug>[-\w]+)/$', views.show_product, name='catalog_product'),
] 

目錄models.py ：

from django.db import models
from django.urls import reverse

# Create your models here.
class Category(models.Model):      
    name = models.CharField(max_length=50)      
    slug = models.SlugField(max_length=50, unique=True,
        help_text='Unique value for product page URL, created from name.')      
    description = models.TextField()      
    is_active = models.BooleanField(default=True)      
    meta_keywords = models.CharField("Meta Keywords", max_length=255,help_text='Comma-delimited set of SEO keywords for meta tag')
    meta_description = models.CharField("Meta Description", max_length=255, help_text='Content for description meta tag')
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)      
    
    class Meta:           
        db_table = 'categories'           
        ordering = ['-created_at']           
        verbose_name_plural = 'Categories'      
        
    def __unicode__(self):           
        return self.name

    def get_absolute_url(self):           
        return reverse('catalog:catalog_category', (), { 'category_slug': self.slug }, current_app='catalog')

這是模板試圖通過反向 function 檢索絕對鏈接：

<h3>Categories</h3> 
{% for c in active_categories %}      
<a href="{{ c.get_absolute_url }}"></a>{{ c.name }}</a><br /> 
{% endfor %}

目錄可通過自定義上下文處理器獲得：

from catalog.models import Category 
from shop import settings 

def shop(request):      
    return {
        'active_categories': Category.objects.filter(is_active=True),
        'site_name': settings.SITE_NAME,           
        'meta_keywords': settings.META_KEYWORDS,           
        'meta_description': settings.META_DESCRIPTION,           
        'request': request}

我已經嘗試通過一些關於命名空間注冊的堆棧回答問題來解決這個問題，但我失敗了。 我仍然在運行服務器時收到此錯誤：

NoReverseMatch at /

'catalog' is not a registered namespace

我在這里做什么錯了？

Answer 1

reverse(viewname, urlconf=None, args=None, kwargs=None, current_app=None)

你不應該把empty set ()反向傳給urlconf function，刪掉

def get_absolute_url(self):
   return reverse('catalog:catalog_category', kwargs={ 'category_slug': self.slug }, current_app='catalog')