Question

所以我有这个名为Events的类，我试图从我的服务器调用异步函数。我试图了解我出错的地方/如何解决另一个异步调用中的承诺。任何提示或提示将不胜感激。

这是我打电话的事件功能：

Event.prototype.getCost = function(name_of_place){
 return new Promise( function(){
      var placeID;
      var GooglePlaces = require("node-googleplaces");
      const places = new GooglePlaces(API_KEY);
      const params = {
           location: '40.689247,-123.102192',
           radius: 1000
      };
      var query =
      {
            query: name_of_place
       };
       // ASYNC call
       places.textSearch(query).then((res) => {
            console.log("FIRST ASYNC CALL");
            console.log(res.body.results[0].place_id);
            placeID = res.body.results[0].place_id;
            var request_place_details={
                 placeid : placeID
            };
            console.log(request_place_details);

            return request_place_details;

       }).then((request_place_details) => {
            console.log("SECOND ASYNC CALL");
            places.details(request_place_details).then((res) => {
                 console.log(res.body.result.price_level + "   S");
                 var cost = res.body.result.price_level;
                 //trying to resolve getCost promise
                 //resolve(this.cost);
                 return cost;
            }).then((cost) => {
                 console.log("ATTEMPT TO RESOLVE ORIGINAL");
                 this.cost = cost;
                 console.log(cost + "   F");

                 //WANT TO RETURN THIS VALUE IN THE END
                 resolve(this.cost);
            });
       });
  })};

这是我从以下地方调用的地方：

//Server is currently serving on port 8420
app.listen(8420,function startServer(){
 console.log("Listening on :: " + 8420);
 var Event1 = new events(7,10,'New York');
 // console.log(Event1.getCost('Sushi'));
 Event1.getCost('Sushi').then(res => {
      console.log(res);
 })
});

Answer 1

你的整个结构是复杂的。剥离注释时，可以将代码减少到：

Event.prototype.getCost = function(name_of_place){
    var GooglePlaces = require("node-googleplaces");
    const places = new GooglePlaces(API_KEY);
    //const params = {
    //  location: '40.689247,-123.102192',
    //  radius: 1000
    //};

    return places.textSearch({ query: name_of_place })
        .then(res => res.body.results[0].place_id)
        .then(placeID => places.details({ placeid : placeID }))
        .then(res => res.body.result.price_level)
}

Answer 2

您没有正确宣布承诺，df['CAGR'] = (first_column.div(second_column).pow(1./2)- 1)).sub(1))*100

然后你可以这样使用

return new Promise( function(resolve, reject){}

另外参考，请查看承诺docs。

尝试从ES6类函数中解析promise链

2 个答案: