Forms and generic views

1. Write a simple form

   <!-- 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>
   

   # polls/urls.py
   path('<int:question_id>/vote/', views.vote, name='vote'),
   

   # polls/views.py
   from django.http import HttpResponse, HttpResponseRedirect
   from django.shortcuts import get_object_or_404, render
   from django.urls import reverse
   
   from .models import Choice, Question
   # ...
   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,)))
   

   # 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})
   

   <!-- 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>
   

2. Use generic views: Less code is better

   # Amend URLconf
   polls/urls.py
   from django.urls import path
   
   from . import views
   
   app_name = 'polls'
   urlpatterns = [
       path('', views.IndexView.as_view(), name='index'),
       path('<int:pk>/', views.DetailView.as_view(), name='detail'),
       path('<int:pk>/results/', views.ResultsView.as_view(), name='results'),
       path('<int:question_id>/vote/', views.vote, name='vote'),
   ]
   

   # Amend views
   # polls/views.py
   from django.http import HttpResponseRedirect
   from django.shortcuts import get_object_or_404, render
   from django.urls import reverse
   from django.views import generic
   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 five published questions."""
           return Question.objects.order_by('-pub_date')[:5]
   
   class DetailView(generic.DetailView):
       model = Question
       template_name = 'polls/detail.html'
   
   class ResultsView(generic.DetailView):
       model = Question
       template_name = 'polls/results.html'
   
   def vote(request, question_id):
       ... # same as above, no changes needed.