Django 模板未正确显示

Question

几个月前离开 Django 后，我又回到了它，并回到了我根据教程制作的民意调查应用程序。我添加了总票数和百分比。百分比，例如，显示特定民意调查选项占总票数的百分比。没有错误，什么也没有。它只是根本不显示。我的意思是，除了百分比之外，一切都显示出来。就像我从来没有在模板中写过它一样！

results.html：

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

<ul>
{% for choice in poll.choice_set.all %}
    <li>{{ choice.choice }} - {{ choice.percentage }} ({{ choice.votes }}) </li>
{% endfor %}
</ul><br /><br />
<p>Total votes for this poll: {{ total }} </p>

views.py：

def results(request, poll_id):
    p = get_object_or_404(Poll, pk=poll_id)
    choices = list(p.choice_set.all())
    total_votes = sum(c.votes for c in choices)
    percentage = {}

    for choice in choices:
        vote = choice.votes
        vote_percentage = int(vote*100.0/total_votes)
        choice.percentage = vote_percentage

    return render_to_response('polls/results.html', {'poll': p, 'total': total_votes}, context_instance=RequestContext(request))

帮助？ ：P

谢谢

编辑：

我尝试了伊格纳西奥的解决方案，但仍然不行。

Answer 1

您不能像模板中那样对变量建立索引。我建议以另一种方式进行：

for choice in choices:
   ...
  choice.percentage = vote_percentage

...

{% for choice in poll.choice_set.all %}
    <li>{{ choice.choice }} - {{ choice.percentage }} ({{ choice.votes }}) </li>
{% endfor %}

Answer 2

您正在查询选项两次。进入视图 choices = list(p.choice_set.all()) 后，再次进入模板 {% for choice in poll.choice_set.all %}。这意味着您的计算将永远不会被使用。如果你想计算视图中的百分比并在模板中访问它，那么你需要在 context: 中传递它，

def results(request, poll_id):
    ...
    return render_to_response('polls/results.html', {'poll': p, 'total': total_votes, 'choices': choices}, context_instance=RequestContext(request))

然后在模板中访问它：

{% for choice in choices %}
    <li>{{ choice.choice }} - {{ choice.percentage }} ({{ choice.votes }}) </li>
{% endfor %}

Answer 3

快速&肮脏的答案：

# views.py
def results(request, poll_id):
    p = get_object_or_404(Poll, pk=poll_id)
    # XXX code smell: one shouldn't have to turn a queryset into a list
    choices = list(p.choice_set.all())

    # XXX code smell: this would be better using aggregation functions
    total_votes = sum(c.votes for c in choices)

    # XXX code smell: and this too   
    for choice in choices:
       vote = choice.votes
       vote_percentage = int(vote*100.0/total_votes)
       choice.percentage = vote_percentage

  context = {
      'poll': p, 
      'total': total_votes, 
      'choices'  :choices
      }
  return render_to_response(
      'polls/results.html',
      context,
      context_instance=RequestContext(request)
      )

在模板中：

 {% for choice in choices %}
    <li>{{ choice.choice }} - {{ choice.percentage }} ({{ choice.votes }}) </li>
 {% endfor %}

但这并没有很好地利用orm和底层数据库——使用注释和聚合函数会更好。