sails.js控制器从一个诺言中获取数据

Question

[我正在尝试使用sails.js（使用node.js）。我有一个控制器，如下所示。该控制器将在URL参数中传递的标准URL解析为ical_url我试图解析它，并建立一个标准化的json objetc pe rmy需要。我有一个parse功能仅暴露在此控制器之外。使用节点式npm包（https://www.npmjs.com/package/node-ical）解析内容。在ical.fromURL方法中，我有一个回调函数初始化变量normalized_data并在其中存储数据。我打算使用这些数据并调用decorate方法进行一些处理，然后返回json。请查看以//>>>>>>开头的行，按照我的意愿，我没有访问normalized_data根据https://github.com/jens-maus/node-ical/blob/HEAD/index.js#L87 ical.fromURL正在返回承诺但我很难理解如何使用该承诺中的数据。有人可以帮我进行此文件（尤其是parse方法中的文件）所需的更改以符合我的期望吗？预先感谢。

/**
 * IcalsController
 */

const ical = require('node-ical');
const months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
const days = ['Sun', 'Mon', 'Tue', 'Wed', 'Thur', 'Fri', 'Sat'];

function normalize(ev_obj) {
    return {
        "uid": ev_obj.uid,
        "start": ev_obj.start.toDateString(),
        "end": ev_obj.end.toDateString(),
        "start_ts": ev_obj.start,
        "end_ts": ev_obj.end,
        "user": ev_obj.organizer.val.split("mailto:")[1].split("@")[0], //TODO - use regex for extraction
        "summary": ev_obj.summary,
        "categories": ev_obj.categories,
        "all_day": (ev_obj["event-allday"] == "true")
    }
}

function decorate(data) {
    //do something here and return a json object
    //return json_object;
}

module.exports = {
  parse: function (req, res) {
    if (req.param("ical_url") == undefined) {
        return res.status(400).send("ical_url is missing");
    } 

    ical.fromURL( //refer - https://github.com/jens-maus/node-ical/blob/HEAD/index.js#L87
        req.param("ical_url"),
        {},
        function (err, data) {
          let normalized_data = [];
            for (let k in data) {
              if (data.hasOwnProperty(k)) {
                if (data[k].type == 'VEVENT') {     
                  normalized_data.push(normalize(data[k]));
                }
              }
            }
          }
        );

    //>>>>>> Here I want to call decorate function and pass normalized_data as parameter
    let result = decorate(normalized_data)
    return res.send(result);
  },
};

Answer 1

问题出在不考虑fromURL方法的异步性质。

代码正在调用fromURL，这将导致在将来某个时间该方法完成时调用回调，然后立即尝试将尚未接收到的数据作为对客户端的响应来发送。] >

您需要在异步操作完成并且实际上已经收到一些数据之后发送响应，更像这样：

parse: function (req, res) {
    if (req.param("ical_url") == undefined) {
        return res.status(400).send("ical_url is missing");
    } 

    ical.fromURL( //refer - https://github.com/jens-maus/node-ical/blob/HEAD/index.js#L87
        req.param("ical_url"),
        {},
        function (err, data) {
          let normalized_data = [];
            for (let k in data) {
              if (data.hasOwnProperty(k)) {
                if (data[k].type == 'VEVENT') {     
                  normalized_data.push(normalize(data[k]));
                }
              }
            }
           res.send(decorate(normalized_data)); << Response moved inside the callback.
          }
        );
  }
尽管我实际上会建议，但您可以使用async/await关键字作为更简洁的解决方案。

parse: async function (req, res) { << Mark method as async
    if (req.param("ical_url") == undefined) {
        return res.status(400).send("ical_url is missing");
    } 
    // Await keyword lets us use data from a promise more like it were simpler synchronous code
    const raw_data= await ical.fromURL( //refer - https://github.com/jens-maus/node-ical/blob/HEAD/index.js#L87
        req.param("ical_url"),
        {}); 
    let normalized_data = [];
    // Do your normalization of raw_data here
    return res.send(decorate(noramlized_data));}