Added the initial version of PollForm.

polls/forms.py

@@ -0,0 +1,17 @@
+from django import forms
+from polls.models import Choice
+
+
+class PollForm(forms.Form):
+    def __init__(self, *args, **kwargs):
+        # We require an ``instance`` parameter.
+        self.instance = kwargs.pop('instance')
+
+        # We call ``super`` (without the ``instance`` param) to finish
+        # off the setup.
+        super(PollForm, self).__init__(*args, **kwargs)
+
+        # We add on a ``choice`` field based on the instance we've got.
+        # This has to be done here (instead of declaratively) because the
+        # ``Poll`` instance will change from request to request.
+        self.fields['choice'] = forms.ModelChoiceField(queryset=Choice.objects.filter(poll=self.instance.pk), empty_label=None, widget=forms.RadioSelect)

polls/tests.py

@@ -63,14 +63,14 @@ def test_bad_votes(self):
         # Send no POST data.
         resp = self.client.post(reverse('polls_vote', kwargs={'poll_id': 1}))
         self.assertEqual(resp.status_code, 200)
-        self.assertEqual(resp.context['error_message'], "You didn't select a choice.")
+        self.assertEqual(resp.context['form']['choice'].errors, [u'This field is required.'])
 
         # Send junk POST data.
         resp = self.client.post(reverse('polls_vote', kwargs={'poll_id': 1}), {'foo': 'bar'})
         self.assertEqual(resp.status_code, 200)
-        self.assertEqual(resp.context['error_message'], "You didn't select a choice.")
+        self.assertEqual(resp.context['form']['choice'].errors, [u'This field is required.'])
 
         # Send a non-existant Choice PK.
         resp = self.client.post(reverse('polls_vote', kwargs={'poll_id': 1}), {'choice': 300})
         self.assertEqual(resp.status_code, 200)
-        self.assertEqual(resp.context['error_message'], "You didn't select a choice.")
+        self.assertEqual(resp.context['form']['choice'].errors, [u'Select a valid choice. That choice is not one of the available choices.'])

polls/views.py

@@ -2,6 +2,7 @@
 from django.http import HttpResponseRedirect, HttpResponse
 from django.shortcuts import render_to_response, get_object_or_404
 from django.template import RequestContext
+from polls.forms import PollForm
 from polls.models import Poll, Choice
 
 
@@ -12,7 +13,8 @@ def index(request):
 
 def detail(request, poll_id):
     p = get_object_or_404(Poll, pk=poll_id)
-    return render_to_response('polls/detail.html', {'poll': p},
+    form = PollForm(instance=p)
+    return render_to_response('polls/detail.html', {'poll': p, 'form': form},
                                context_instance=RequestContext(request))
 
 
@@ -24,18 +26,19 @@ def results(request, poll_id):
 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_to_response('polls/detail.html', {
-            'poll': p,
-            'error_message': "You didn't select a choice.",
-        }, context_instance=RequestContext(request))
+    if request.method == 'POST':
+        form = PollForm(request.POST, instance=p)
+
+        if form.is_valid():
+            choice = form.cleaned_data['choice']
+            choice.votes += 1
+            choice.save()
+
+            return HttpResponseRedirect(reverse('polls_results', kwargs={'poll_id': p.id}))
     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', kwargs={'poll_id': p.id}))
+        form = PollForm(instance=p)
+
+    return render_to_response('polls/detail.html', {
+        'poll': p,
+        'form': form,
+    }, context_instance=RequestContext(request))

templates/polls/detail.html

@@ -4,9 +4,6 @@ <h1>{{ poll.question }}</h1>
 
 <form action="{% url polls_vote poll_id=poll.id %}" method="post">
 {% csrf_token %}
-{% for choice in poll.choice_set.all %}
-    <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}" />
-    <label for="choice{{ forloop.counter }}">{{ choice.choice }}</label><br />
-{% endfor %}
+{{ form.as_p }}
 <input type="submit" value="Vote" />
 </form>