title: Django: Reverse for 'detail' with arguments '('',)' and keyword arguments '{}' not found
body: <p>I'm following the official tutorial to learn Django and using 1.5.</p>
  
  <p>I had this link as part of my index template, which was working fine:</p>
  
  <pre><code>&lt;li&gt;&lt;a href="/polls/{{ poll.id }}/"&gt;{{ poll.question }}&lt;/a&gt;&lt;/li&gt;
  </code></pre>
  
  <p>however, this is hardcoded and the tutorial suggested a better way was to use:</p>
  
  <pre><code>&lt;li&gt;&lt;a href="{% url 'detail' poll.id %}"&gt;{{ poll.question }}&lt;/a&gt;&lt;/li&gt;
  </code></pre>
  
  <p>so that you'll be better of when dealing with huge number of templates and u have to make changes to the url.</p>
  
  <p>Since I made the above change I get the following errors when I run the app:</p>
  
  <pre><code>Exception Type: NoReverseMatch
  Exception Value:    Reverse for 'detail' with arguments '('',)' and keyword arguments '{}' not found.
  </code></pre>
  
  <p>My urls.py looks like this:</p>
  
  <pre><code>from django.conf.urls import patterns, url
  
  from polls import views
  
  urlpatterns = patterns('',
      url(r'^$', views.index, name='index'),
      url(r'^(?P&lt;poll_id&gt;\d+)/$', views.detail, name='detail'),
      url(r'^(?P&lt;poll_id&gt;\d+)/results/$', views.results, name='results'),
     url(r'^(?P&lt;poll_id&gt;\d+)/vote/$', views.vote, name='vote'),                     
  )
  </code></pre>
  
  <p>views.py looks like this:</p>
  
  <pre><code>from django.shortcuts import render, get_object_or_404
  from django.http import Http404
  
  from polls.models import Poll
  
  def index(request):
      latest_poll_list = Poll.objects.order_by('-pub_date')[:5]
      context = {'latest_poll_list': latest_poll_list}
      return render(request, 'polls/index.html', context)
  
  
  def detail(request, poll_id):
      poll = get_object_or_404(Poll, pk = poll_id)
      return render(request, 'polls/detail.html', {'poll': poll})
  </code></pre>
  
  <p>my index.html template looks like this:</p>
  
  <pre><code>{% if latest_poll_list %}
      &lt;ul&gt;
      {% for poll in latest_poll_list %}
          &lt;li&gt;&lt;a href="{% url 'polls:detail' poll_id %}"&gt;{{ poll.question }}&lt;/a&gt;&lt;/li&gt;
      {% endfor %}
      &lt;/ul&gt;
  {% else %}
      &lt;p&gt; No polls are available.&lt;/p&gt;
  {% endif %}
  </code></pre>
  
  <p>Usually I could easily read where the error is coming from and deal with it but in this case I can't spot the cause of the error hence I'm unable to progress with my study.
  Any help will be greatly appreciated.</p>