我在浏览器中请求该接口正常返回数据，

但是在小程序使用云函数调用该接口，返回信息却是appkey为空？

云函数代码：

const appkey = '885595fd63350f83';


const cloud = require('wx-server-sdk')
const TcbRouter = require('tcb-router'); 
const rq = require('request');
cloud.init()


// 云函数入口函数
exports.main = async(event, context) => {
      const app = new TcbRouter({
            event
      });
      //根据isbn码获取图书详情信息
      app.router('bookinfo', async(ctx) => {
            ctx.body = new Promise(resolve => {
                  rq({
                        url: 'https://api.jisuapi.com/isbn/query?appkey=' + appkey + '&isbn=' + event.isbn,
                        method: "GET",
                        json: true,
                  }, function(error, response, body) {
                        resolve({
                              body: body
                        })
                  });
            });
      });
      return app.serve();
}

调用代码：            let that = this;
            wx.cloud.callFunction({
                  name: 'books',
                  data: {
                        $url: "bookinfo", //云函数路由参数
                        isbn: bn
                  },
                  success: res => {
                        console.log(res);
                        if (res.result.body.status == 0) {
                              
                              db.collection('books').add({
                                    data: res.result.body.result,
                                    success: function(res) {
                                          wx.hideLoading();
                                          that.setData({
                                                bookinfo: res.result.body.result,
                                                show_a: false,
                                                show_b: true,
                                                show_c: false,
                                                active: 1,
                                          })
                                    },
                                    fail: console.error
                              })
                        }else{
                              console.log("status not 0");
                        }
                  } ,
                  fail: err => {
                        console.error(err)
                  } 

            })

控制台打印 res: