public HttpResponse vote(HttpRequest request, Long poll_id) throws HttpException {
Poll p = javango.getObjectOr404(Poll.class, poll_id);
VoteForm form = javango.newForm(VoteForm.class).setPoll(p);
form.bind(request.getParameterMap());
if (!form.isValid()) {
Map<String, Object> context = new HashMap<String, Object>();
context.put("poll", p);
context.put("error_message", "You didn't select a valid choice");