Context from 'views.py' not showing on 'base.html' - Django

Question

I can't find where is the problem, so I want to create li element for each of my categories. Here are my codes:

views.py:

def categories(request):
    context = {
        'category_list':  Category.objects.all(),
    }
    return render(request, 'base.html', context)    

base.html:

<nav id="header-nav">
<ul id="nav-ul" class="menu font-reg clearfix">
<li class="menu-item menu-item-has-children">
<a href="">Blog<span class="sub-drop-icon fa fa-angle-down"></span></a>
<ul class="sub-menu sub-menu-first">
{% for category in category_list %}
<li><a href="#">{{ category.name }}</a></li>
{% endfor %}
</ul>
</li>
<li class="menu-item menu-item-has-children">
<a href="about-1.html">About</a>
</li>
<li class="menu-item menu-item-has-children">
<a href="contact-1.html">Contact</a>
</li>
</ul>
</nav>

urls.py:

urlpatterns = [
    path('', views.index),
    path('article/<slug:article_slug>', views.article, name='article'),
]

Category class:

class Category(models.Model):
    def __str__(self):
        return self.name
    name = models.CharField(max_length=20)

Answer 1

To show the article and categories on the same page, you can do as follows:

urls.py

urlpatterns = [
    path('', views.index),
    path('article/<slug:article_slug>', views.article, name='article'),
]

models.py

It's better to put def __str__ below all the fields.

class Category(models.Model):
    name = models.CharField(max_length=20)

    def __str__(self):
        return self.name

views.py

You need to pass the article and the categories in one view.

def article(request, slug):
    context = {
        'article': Article.objects.get(slug=slug),
        'category_list':  Category.objects.all()
    }
    return render(request, 'base.html', context)

base.html

To show a list of categories:

{% for category in category_list %}
    <li><a href="#">{{ category.name }}</a></li>
{% endfor %}

Note:

It will have much more sense to create a separate article.html page with {% extends 'base.html' %} line in the beginning to render your article. Moreover, pay attention to Class-based views for simple rendering lists and detail info for instances of your Models.