NoReverseMatch at / polls / 1 / vote /关注Django的官方教程

Question

我正在关注Django教程。在建立投票表格的那一刻，我已经达到了第4部分。遗憾的是，我找不到导致以下错误的问题：

  

NoReverseMatch at / polls / 1 / vote /

     

反向投票＆＃39;有参数＆＃39;（＆＃39;＆＃39;，）＆＃39;和关键字参数＆＃39; {}＆＃39;未找到。尝试了1种模式：[u＆＃39;民意调查/（？P [0-9] +）/投票/ $＆＃39;]

/polls/1/vote和/polls/1/都会引发上述错误。

我的polls/urls.py

from django.conf.urls import url

from . import views

app_name = 'polls'
urlpatterns = [
    url(r'^$', views.index, name='index'),
    url(r'^(?P<question_id>[0-9]+)/$', views.details, name='details'),
    url(r'^(?P<question_id>[0-9]+)/results/$', views.results, name='results'),
    url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),
]

这里是details.html，显示第11行的错误，form开头标记：

<h1>{{ question.question }}</h1>

{% if error %}
    <p>
    <strong>
        {{ error  }}
    </strong>
    </p>
{% endif %}

<form action="{% url 'polls:vote' question_id %}" method="POST">
    {% csrf_token  %}
    {% for choice in question.choice_set.all %}
    <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}"/>
    <label for="choice{{ forloop.counter }}">{{ choice.choice }}</label>
    <br/>
    {% endfor %}
    <input type="submit" value="Vote">
</form>