Django基础，Day5 - form表单投票详解

投票URL

polls/urls.py：

# ex: /polls/5/vote/
 url(r'^(?P<question_id>[0-9]+)/vote/$', views.vote, name='vote'),

创建投票form表单

polls/templates/polls/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>

代码解释：

{{ forloop.counter }} : for 循环次数

{% csrf_token %} : 解决POST请求跨域问题 Cross Site Request Forgeries

{% if %} {% endif %}:判断

{% for %} {% endfor %}:循环

投票Views 逻辑处理

投票 views vote in polls/views.py：

from django.http import HttpResponse, HttpResponseRedirect
from django.urls import reverse

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,)))

代码解释：

request.POST,request.GET：分别可获得POST或GET方法的参数值，如上 request.POST['choice'] 可取得POST请求中，name值为choice的Value值。若POST参数中没有choice，则会产生KeyError。

HttpResponseRedirect：重定向跳转，提交成功后进行自动重定向跳转是web 开发的一个良好实践。防止数据提交两次。

投票结果页 Views 逻辑处理

views results in polls/views.py:

from django.shortcuts import get_object_or_404, render

def results(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/results.html', {'question': question})

投票结果显示 template

polls/templates/polls/results.html：

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

<ul>
    {% for choice in question.choice_set.all %}
        <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
    {% endfor %}
</ul>

<a href="{% url 'polls:detail' question.id %}">Vote again?</a>