请问一个Promise 的问题？

  home_barlist1: function home_barlist1() {
    //获取中间导航 
    var that = this;
    _wxRequest2.default.post({
      'url': _api2.default.home_barlist,
      'data': {
        show_type: 4
      }
    }).then(function (res) {
      if (res.code == 100) {
        var homelist = res.data;
        that.setData({
          homelist1: homelist
        });
      } else {
        _tip2.default.toast(res.data);
      }
    });
  },

请问上面这段代码，我想封装成Promise 这种 直接调用this.home_barlist1().then 该怎么改呢？

我改成下面这样 好像不行

 home_barlist1: function home_barlist1() {
    //获取中间导航 
  return new Promise(function (resolve, reject) {
    var that = this;
    _wxRequest2.default.post({
      'url': _api2.default.home_barlist,
      'data': {
        show_type: 4
      }
    }).then(function (res) {
      if (res.code == 100) {
        var homelist = res.data;
        that.setData({
          homelist1: homelist
        });
        resolve(res);
      } else {
        _tip2.default.toast(res.data);
      }
    });
   });
 },