docs: def build_contact(request, slug=""):
      """
      Builds appropriate contact form based on options
      set in the contact_form controller.
      """
      controller = get_object_or_404(ContactFormController, slug=slug)
      site = Site.objects.get_current()
      UserModel = get_user_model()
      user = request.user
      form = ContactForm(request.POST or None, request.FILES or None, controller=controller)
  
      # if we know, fill in the user name and email
      if user.is_authenticated:
          # first, resolve username for tango and non-tango sites
          try:
              name = user.display_name
          except AttributeError:
              name = user.username
          form.fields['sender_name'].widget.attrs['readonly'] = 'true'
          form.fields['sender_name'].initial = name
          form.fields['sender_email'].widget.attrs['readonly'] = 'true'
          form.fields['sender_email'].initial = user.email
  
      if form.is_valid():
          if controller.store_in_db:
              # To do: sanitize submission.
              new_msg = Contact(**form.cleaned_data)
              new_msg.controller = controller
              new_msg.site = site
              if controller.override_subject:  # we're overriding the subject
                  new_msg.subject = controller.override_subject
              new_msg.save()
  
          if controller.send_emails:
              form_data = form.cleaned_data
              if controller.override_subject:
                  subject = controller.override_subject
              elif 'subject' in form_data:
                  subject = form_data['subject']
              else:
                  subject = "{} message from {}".format(controller.name, form_data['sender_name'])
  
              body = "{} \n\n {}".format(form_data['body'], form_data['sender_name'])
              if controller.request_contact_info:
                  body += "\nAddress: {} \nCity: {} \nState: {} \nPhone: {}".format(
                      form_data['contact_address'],
                      form_data['contact_city'],
                      form_data['contact_state'],
                      form_data['contact_phone']
                  )
  
              if controller.email_options == '2':  # Create selectable list from recipients
                  try:
                      to = [UserModel.objects.get(username=form.cleaned_data['to']).email]
                  except Exception:
                      to = [form.cleaned_data['to']]
  
              if controller.email_options == '1':
                  to = [r.email for r in controller.recipients.all()]
                  for r in controller.other_recipients.all():
                      to.append(r.email)
  
              if 'send_a_copy' in form.cleaned_data:
                  to.append(form.cleaned_data['sender_email'])
  
              mail = EmailMessage(
                  subject=subject,
                  body=body,
                  from_email=form.cleaned_data['sender_email'],
                  to=to
              )
              if 'photo' in request.FILES:
                  photo = request.FILES['photo']
                  mail.attach(photo.name, photo.read(), photo.content_type)
              mail.send()
          return render(request, 'success_url', {'controller': controller})
  
      return render(request, 'contact/form.html', {
          'form': form,
          'site': site,
          'controller': controller
      })