未找到参数为 '('',)' 的 'single' 反转尝试了 1 个模式：['(?P<slug>[-a-zA-Z0-9_]+)/$']

如何解决未找到参数为 '('',)' 的 'single' 反转尝试了 1 个模式：['(?P<slug>[-a-zA-Z0-9_]+)/$']

我运行了这段代码，它运行良好。几天后我再次打开它，它在除 add/ 页面之外的所有页面中都抛出了错误。 错误代码：django.urls.exceptions.noreverseMatch: Reverse for 'single' with arguments '('',)' not found. 1 pattern(s) tried: ['(?P<slug>[-a-zA-Z0-9_]+)/$'] 我试着在这里阅读其他类似的问题，但他们没有解决问题

models.py

class Core(models.Model):
    title = models.CharField(max_length=200)
    excerpt = models.TextField()
    author = models.ForeignKey(User,on_delete=models.CASCADE,related_name='core')
    slug = models.SlugField(max_length=100,unique=True)
    updated = models.DateTimeField(auto_Now=True)
    published = models.DateTimeField(default=timezone.Now)

    def get_absolute_urls(self):
        return reverse('core:single',args=[self.slug])
    
    def __str__(self):
        return self.title

    class Meta:
        ordering = ['-published']

urls.py

app_name = 'core'

urlpatterns = [
    path('',views.IndexView.as_view(),name='index'),path('add/',views.AddView.as_view(),name='add'),path('posts/',views.PostsView.as_view(),name='posts'),path('<slug:slug>/',views.SingleView.as_view(),name='single'),]

views.py

class IndexView(ListView):
    model = Core
    template_name = 'core/index.html'
    context_object_name = 'index'

class SingleView(DetailView):
    model = Core
    template_name = 'core/single.html'
    context_object_name = 'post'

class PostsView(ListView):
    model = Core
    template_name = 'core/posts.html'
    context_object_name = 'post_list'

class AddView(CreateView):
    '''Basically a form. Someone types in and add new post'''
    model = Core
    template_name = 'core/add.html'
    fields = '__all__' #take all the fields from the db and put that into a form
    success_url = reverse_lazy('core:posts')
    

single.html

{% extends 'core/base.html' %}

{% block content %}
<div class="container">
    <div class="row">
        <div class="col-12 pt-5">
            <img src="https://source.unsplash.com/random/1600x900" alt="" class="card-img-top">
            <h2 class="pt-5">{{ post.title}}</h2>
            <p>{{ post.excerpt }}</p>
        </div>
    </div>
</div>
{% endblock%}

index.html

{% extends 'core/base.html' %}

{% block content %}
<div class="album py-5 bg-light">
    <div class="container">  
        <div class="row">
            {% for core in index %}
                <div class="col-md-4">
                    <div class="card mb-4 Box-shadow">
                        <img src="https://source.unsplash.com/random/800x600" alt="card image cap" class="card-img-top">
                        <div class="card-body">
                            <h4><a href="{{ core.get_absolute_urls }}">{{ core.title }}</a></h4>
                            <p class="card-text"></p>
                            <div class="d-flex justify-content-between align-items-center">
                                <div class="">
                                    <small class="text-muted">9 mins</small>
                                </div>
                            </div>
                        </div>
                    </div>
                </div>
            {% endfor %}
        </div>
    </div>
</div>
{% endblock %}

抱歉问了这么长的问题

2. 其次，除了 Django 自己的文档之外，对可以帮助我全面了解 Django URL 的材料有什么建议吗？网址给我带来了很多困难

解决方法

您的网址中缺少一个 slug 项目。

无论您如何设计 URL，它都应该是这样的。