title: NoReverseMatch Django: keyword arguments
body: <p>Why does this return <code>NoReverseMatch</code>?</p>
  
  <p>html:</p>
  
  <pre><code>{% url vote thing.id thing.slug %}
  </code></pre>
  
  <p>urls.py:</p>
  
  <pre><code>url(r'^vote/(?P&lt;object_id&gt;\d+)/(?P&lt;slug&gt;[w\-]+)/$', 'app.views.the_view', name='vote'),
  </code></pre>
  
  <p>views.py:</p>
  
  <pre><code>def the_view(request, object_id, slug):
      thing_list = Thing.objects.all()
      return render(request, 'vote.html', {'thing_list':thing_list})
  </code></pre>