Django -- Form

---

detail.html

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

{% if error_message %}<p><strong>{{ error_message }}</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_text }}</label><br />
{% endfor %}
<input type="submit" value="Vote" />
</form>

 {% csrf_token %} 提交表单首先要做的，用于防止跨域攻击

 {{ forloop.counter }} for标签自带的变量，统计for循环的次数

 method="post"，涉及数据库改变的药用post方法

---

urls.py

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

---

views.py

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        # Redisplay the question voting form.
        return render(request, 'polls/detail.html', {
            'question': question,
            'error_message': "You didn't select a choice.",
        })
    else:
        selected_choice.votes += 1
        selected_choice.save()
        # Always return an HttpResponseRedirect after successfully dealing
        # with POST data. This prevents data from being posted twice if a
        # user hits the Back button.
        return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

request.POST是一个字典，键为input中的name，值为value

  HttpResponseRedirect 处理完POST请求后要返回这个，而不是普通的HTTPResponse。能够避免数据被提交两次（用户按返回键时）

reverse 避免硬编码，会自动生成一个URL字符串