Writing your first Django app, part 4

4-1. Forms

Lab:

*** edit polls/urls.py
*** edit polls/views.py
*** edit polls/templates/polls/detail.html
*** add polls/templates/polls/vote.html
*** add polls/templates/polls/result.html
. go
  • polls/urls.py:

    from django.urls import path
    from . import views
    app_name = 'polls'
    
    urlpatterns = [
      path('', views.index, name='index'),
      path('<int:question_id>/', views.detail, name='detail'),
      path('<int:question_id>/vote/', views.vote, name='vote'),
      path('<int:question_id>/results/', views.results, name='results'),
    ]
    
  • 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 index(request):
        latest_question_list = Question.objects.order_by('-pub_date')[:5]
        context = {'latest_question_list': latest_question_list}
        return render(request, 'polls/index.html', context)
    
    def detail(request, question_id):
        question = get_object_or_404(Question, pk=question_id)
        return render(request, 'polls/detail.html', {'question': 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,)))
    
    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/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/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>
    
../_images/img4-1-1-v2.png
../_images/img4-1-2-v2.png

Note

Able to vote