text: from django.http import HttpResponse, HttpResponseRedirect, Http404
  from django.shortcuts import render, get_object_or_404
  from django.urls import reverse
  from django.views import generic
  from django.utils import timezone
  
  from .models import Choice, Question
  
  class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'
  
    def get_queryset(self):
      """Return the last seven published questions (not including those set to by published in the future)"""
      return Question.objects.filter(pub_date__lte=timezone.now()).order_by('-pub_date')[:7]
  
  class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'
  
    def get_queryset(self):
      """Excludes any question that aren't published yet"""
      return Question.objects.filter(pub_date__lte=timezone.now())
  
  class ResultsView(generic.DetailView):
    model = Question
    template_name = 'polls/results.html'
  
  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, )))
  
  