i am learning django from official django tutorial. and i am getting this error when vote something from form. this caused from - probably - vote function under views.py

here is my views.py / vote function :

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):return render_to_response('polls/detail.html', {'poll':p,'error_message' : "didint select anything ",}, context_instance= RequestContext(request))else:selected_choice.votes += 1selected_choice.save()return HttpResponseRedirect(reverse('polls.views.results', args=(p.id,)))

and this is error message screen :

**ValueError at /polls/2/vote/

invalid literal for int() with base 10: 'on'**

Request Method: POST Request URL: 127.0.0.1:8000/polls/2/vote/

Django Version: 1.4 Exception Type: ValueError Exception Value: invalid literal for int() with base 10: 'on' ExceptionLocation: /usr/local/lib/python2.7/dist-packages/django/db/models/fields/init.pyin get_prep_value, line 537

and here is my polls/urls.py :

from django.conf.urls import patterns, include, url

urlpatterns = patterns('polls.views',

    url(r'^$', 'index'),url(r'^(?P<poll_id>\d+)/$','detail'),url(r'^(?P<poll_id>\d+)/results/$','results'),url(r'^(?P<poll_id>\d+)/vote/$','vote'),

)

and here is project/urls.py :

from django.conf.urls import patterns, include, url

urlpatterns = patterns('polls.views',

    url(r'^$', 'index'),url(r'^(?P<poll_id>\d+)/$','detail'),url(r'^(?P<poll_id>\d+)/results/$','results'),url(r'^(?P<poll_id>\d+)/vote/$','vote'),

)

You'll receive this error when you're trying to cast a string to an integer, but the string doesn't really contain any digits:

i.e.

number = int(string)

From your code, there are three places where I see the use and probable cast of an integer. When p=get_object_or_404(Poll, pk=poll_id) we're making an assumption that you've correctly passed in an integer as poll_id. Could you post the urlpattern you're using associated with this view and an example URL?

You also are making an assumption that request.POST['choice'] will be an integer and can be cast as such. You aren't catching an exception related to this, so you'll want to check what the value of this entry is. I would add in a few other checks for this part:

if request.method=="POST":choice = request.POST.get('choice', None)if choice is not None:selected_choice = p.choice_set.get(pk=choice)
...

These two stand out the most.

Please post your urlpattern and more of the error message you were getting (such as which specific line is throwing your exception).