How to master url magic in Django?

Question

Django

Hello, I recently started dipping into the back-end and started with Django (I poked around the tutorials, it worked, but there was a snag and understanding "why is it not working ?!" is not possible at the moment.
I create a view for the pages and specify them in controller.

def index(request):
    return render(request, 'blog/index.html')

def post_list(request):
    posts = Post.objects.filter(published_date__lte=timezone.now()).order_by('published_date')
    return render(request, 'blog/post_list.html', {'posts': posts})

urlpatterns = [
    url(r'^admin/', include(admin.site.urls)),
    url(r'', include('blog.urls')),
    url(r'^post_list/', include('blog.urls')),
]

urlpatterns = [
    url(r'^$', views.index, name='index'),
    url(r'^$', views.post_list, name='post_list'),

]

urlpatterns += static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
urlpatterns += staticfiles_urlpatterns()

if settings.DEBUG:
    urlpatterns += [
        url(r'^images/(?P<path>.*)$', serve, {'document_root': settings.MEDIA_ROOT}),
    ]

I insert a link into the template
{% url "post_list" %}
When you click on the link, the url in the address bar changes, but the index template remains in its place. Tell me, please, what is the problem?

Answer 1

urlpatterns = [
    url(r'^admin/', include(admin.site.urls)),
    url(r'', include('blog.urls')),
    url(r'^post_list/', include('blog.urls')),
]

here url(r'^post_list/', include('blog.urls')) is removed, it makes no sense to include the same thing twice

urlpatterns = [
    url(r'^$', views.index, name='index'),
    url(r'^$', views.post_list, name='post_list'),
]

and here we make the second url unique, in general, the first match is searched, the rest are ignored