url path from categories in DetailView - django

Question

I use a DetailView to display all elements inside a category.
I am trying to get my category slugs as variables in urls. But I don't know how to make the link between categories and details.
So far when I click on one of the generated link in the Index.html such as http://localhost:8000/oneofthecategories, I get the following error:
Exception Type: FieldError
Exception Value:
Cannot resolve keyword 'slug' into field. Choices are: author, category, category_id, id, title
Files:
#Models.py
class categories(models.Model):
name = models.CharField(max_length=50,unique=True)
slug = models.SlugField(max_length=100,unique=True)
def __str__(self):
return self.name
class details(models.Model):
title = models.CharField(max_length=100)
author = models.CharField(max_length=42)
category = models.ForeignKey('categories', on_delete=models.CASCADE,related_name="detail")
def __str__(self):
return self.title
#Views.py
class IndexView(generic.ListView):
model = categories
context_object_name = "list_categories"
template_name='show/index.html'
class CategoryDetails(DetailView):
model = details
context_object_name = "detail"
template_name = "show/categories.html"
slug_url_kwarg = 'slug'
#Urls.py
urlpatterns = [
path('', views.IndexView.as_view(), name='index'),
path('<slug:slug>', views.CategoryDetails.as_view(), name='category_details'),
]
#Index.html
{% load staticfiles %}
<p>These is a list of categories</p>
{% for category in list_categories %}
<div class="article">
<h3>{{ category.name }}</h3>
{% for detail in category.categories.all %}
<p> {{detail.title}} </p>
<li>URLS</li>
{% endfor %}
</div>