code: def fave_slices(self, user_id=None):
          
          if not user_id:
              user_id = g.user.id
          qry = (
              db.session.query(
                  models.Slice,
                  models.FavStar.dttm,
              )
              .join(
                  models.FavStar,
                  sqla.and_(
                      models.FavStar.user_id == int(user_id),
                      models.FavStar.class_name == 'slice',
                      models.Slice.id == models.FavStar.obj_id,
                  ),
              )
              .order_by(
                  models.FavStar.dttm.desc(),
              )
          )
          payload = []
          for o in qry.all():
              d = {
                  'id': o.Slice.id,
                  'title': o.Slice.slice_name,
                  'url': o.Slice.slice_url,
                  'dttm': o.dttm,
                  'viz_type': o.Slice.viz_type,
              }
              if o.Slice.created_by:
                  user = o.Slice.created_by
                  d['creator'] = str(user)
                  d['creator_url'] = '/superset/profile/{}/'.format(
                      user.username)
              payload.append(d)
          return json_success(
              json.dumps(payload, default=utils.json_int_dttm_ser))
docs: Favorite slices for a user