Python-Django cannot interpret the id in an URL and give "<built-in function id>" instead of redirecting on the rigth page -

i have simple app creates events , add attendees them built django 1.8. work on virtualenv python3. when create event, i'm redirected detail page of event , have possibility add attendees. when add one, django cannot redirect me page of event, cause cannot interpret id , gives me <built-in function id>.

my app event :

models.py

class event(models.model):  name = models.charfield("event title", max_length=255) organizer = models.foreignkey(user) attendees = models.manytomanyfield(user, verbose_name="attendees", blank=true,      through="eventattendees", related_name="%(app_label)s_%(class)s_attendees")   def get_absolute_url(self):     return reverse('event:detail', kwargs={'pk':self.pk})   def delete_url(self):     return reverse('event:delete', kwargs={'pk':self.pk})   def update_url(self):     return reverse('event:update', kwargs={'pk':self.pk})   def __str__(self):     return self.name  class meta:     verbose_name = 'event'     verbose_name_plural = 'events'   class eventattendees(models.model): event = models.foreignkey(event) attendee = models.foreignkey(user)   def delete_url(self):     return "/event/%i/attendee/%i/delete/" % (self.event.id, self.attendee.id)  class meta:     unique_together = (         'event',         'attendee',         ) 

forms.py

class eventform(modelform): class meta:     model = event     fields = ('name',)   class eventattendeesform(modelform): class meta:     model = eventattendees     fields = ('event', 'attendee',)   def __init__(self, *args, **kwargs):     super(eventattendeesform, self).__init__(*args, **kwargs)     self.fields['event'].widget = hiddeninput()      if 'event' in self.initial:         attendees = [user.pk user in self.initial['event'].attendees.all()]         self.fields['attendee'].queryset=user.objects.exclude(pk__in = attendees) 

views.py

class eventcreateview(createview): model = event  form_class = eventform template_name = 'evenement/event/create.html'   def form_valid(self, form):     obj = form.save(commit=false)      o = user.objects.get(username=self.request.user)     obj.organizer = o     obj.save()      return httpresponseredirect(obj.get_absolute_url())   def delete_attendee(request, event_id, attendee_id): if request.method == 'post':     event = event.objects.get(pk = event_id)     attendee = user.objects.get(pk = attendee_id)      to_be_deleted = eventattendees.objects.get(         event = event,          attendee = attendee)     to_be_deleted.delete()     if request.is_ajax():         return httpresponse("ok") return httpresponseredirect('/event/%s/detail/' % event_id)  class eventdetailview(detailview): model = event template_name = 'evenement/event/details.html'  def get_context_data(self, **kwargs):     context = super(eventdetailview, self).get_context_data(**kwargs)     form = eventattendeesform(initial = {'event':self.object})     attendees = [user.pk user in self.object.attendees.all()]     form.fields['attendee'].queryset = user.objects.exclude(pk__in = attendees)     form.fields['event'].widget = hiddeninput()     context['form'] = form     return context   def post(self, request, *args, **kwargs):     form = eventattendeesform(self.request.post)     if form.is_valid():         form.save()         return httpresponseredirect('/event/%s/detail/' %id)     else:         return render(request, 'evenement/event/details.html', {'event': form.instance.event, 'form': form}) 

i think problem located in function post of class eventdetailview, here

return httpresponseredirect('/event/%s/detail/' %id) 

python cannot interpret %id

i wanted join app, don't know how to. many answer.

you have id of item, you're not doing.

if form.is_valid():     obj = form.save()     return httpresponseredirect('/event/%s/detail/' % obj.id)