四、Writing your first Django app, part 4

写一个简单的表单

继续Part 3的例子

1.修改 `polls/detail.html` 模版文件，增加form元素

{
   { poll.question }}
{% if error_message %}{
   { error_message }}
{% endif %}
    
         {% csrf_token %}    {% for choice in poll.choice_set.all %}        
             
     {
   { choice.choice_text }}        
     
    {% endfor %}

注意事项：

增加一些 radio 按钮,按钮的value是choice.id的值，提交的时候通过post中的choice值来处理

使用 method="post" 方法

提交的地址是 {% url 'polls:vote' poll.id %}

forloop.counter 是循环计数变量

使用 {% csrf_token %} 避免跨站攻击

2.增加处理post数据的vote部分

完善polls/views.py

from django.shortcuts import get_object_or_404, renderfrom django.http import HttpResponseRedirect, HttpResponsefrom django.core.urlresolvers import reversefrom polls.models import Choice, Poll# ...def vote(request, poll_id):    p = get_object_or_404(Poll, pk=poll_id)    try:        selected_choice = p.choice_set.get(pk=request.POST['choice'])    except (KeyError, Choice.DoesNotExist):        # Redisplay the poll voting form.        return render(request, 'polls/detail.html', {            'poll': p,            '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=(p.id,)))

代码解读：

使用 request.POST['choice'] 的方法访问 POST 数据

如果在字典访问中找不到 choice key，抛出 KeyError 异常

尽量使用HttpResponseRedirect 代替 HttpResponse

通过使用 reverse()方法来避免在视图中写入硬编码的网址

3.完善结果显示的页面 results()

def results(request, poll_id):    poll = get_object_or_404(Poll, pk=poll_id)    return render(request, 'polls/results.html', {'poll': poll})

4.建立`polls/results.html` 模版文件

{
   { poll.question }}
    
         {% for choice in poll.choice_set.all %}        
     {
   { choice.choice_text }} -- {
   { choice.votes }}         vote{
   { choice.votes|pluralize }}
    {% endfor %}
    
Vote again?

使用通用视图来改写上面的例子

ListView

DetailView

1. 在urls.py中的设置

url(r'^$', views.IndexView.as_view(), name='index'),url(r'^(?P
    
     \d+)/$', views.DetailView.as_view(), name='detail'),

2. 视图中的写法

from django.shortcuts import get_object_or_404, renderfrom django.http import HttpResponseRedirectfrom django.core.urlresolvers import reversefrom django.views import genericfrom polls.models import Choice, Pollclass IndexView(generic.ListView):    template_name = 'polls/index.html'    context_object_name = 'latest_poll_list'    def get_queryset(self):        """Return the last five published polls."""        return Poll.objects.order_by('-pub_date')[:5]class DetailView(generic.DetailView):    model = Poll    template_name = 'polls/detail.html'class ResultsView(generic.DetailView):    model = Poll    template_name = 'polls/results.html'def vote(request, poll_id):    ....