old_contents: from django.conf.urls import patterns, url
  
  from views import CategoryListView
  
  
  urlpatterns = patterns('',
      url(r'^$', CategoryListView.as_view(), name='overview'),
  )
  
new_contents: from django.conf.urls import patterns, url
  
  from views import CategoryListView, ForumDetailView
  
  
  urlpatterns = patterns('',
      url(r'^$', CategoryListView.as_view(), name='overview'),
      url(r'^(?P<pk>\d+)/$', ForumDetailView.as_view(), name='forum'),
  )
  
subject: include forum detail view in urls