python - Django: getting NoReverseMatch at / error -

there lot of similar issues on , went through of them, still unable resolve problem.

i getting following error:

reverse 'category_view' arguments '()' , keyword arguments '{'pk': 'dynamic-programming'}' not found. 0 pattern(s) tried: [] noreversematch @ /articles/

here settings urls.py file:

url(r'^category/(?p<pk>[\w-]+)/$', views.categorydetailview.as_view(), name='category_view') 

and, definition of get_absolute_url() model;

def get_absolute_url(self): return reverse('category_view', kwargs={'pk': self.slug}) 

and caller getting error index.html:

<li><a href="{{ category.get_absolute_url }}">{{ category.name }}</a></li> 

i sure missing obvious, not able figure out past few hours. :(

content project's urls.py:

url(r'^articles/$', include('blog.urls', namespace="blog")),     url(r'^admin/', include(admin.site.urls)), 

i suspect forgot include urls.py app project's urls.py.

update: if used namespace parameter of include have specify namespace in reverse() call:

def get_absolute_url(self):     return reverse('blog:category_view', kwargs={'pk': self.slug})