code: def edit_link(self, inst):
          
          if not inst.is_active:
              return u'--'
          update_url = reverse('admin:{}_{}_add'.format(self.model._meta.app_label, self.model._meta.model_name))
          update_url += "?source={}".format(inst.pk)
          return u'<a href="{}">{}</a>'.format(update_url, _('Update'))
docs: Edit link for the change view