code: def get_preview_kwargs(self, **kwargs):
          
          if not self.pass_through_kwarg:
              return {}
  
          obj = self.get_object()
          return {
              self.pass_through_kwarg: getattr(obj, self.pass_through_attr)
          }
docs: Gets the url keyword arguments to pass to the
          `preview_view` callable. If the `pass_through_kwarg`
          attribute is set the value of `pass_through_attr` will
          be looked up on the object.
  
          So if you are previewing an item Obj<id=2> and
  
              ::
  
                  self.pass_through_kwarg = 'object_id'
                  self.pass_through_attr = 'pk'
  
          This will return
  
              ::
  
                  { 'object_id' : 2 }