Question

我一直在努力了解使用这个简单代码嵌套的承诺。

我调用的两个函数都是异步的，一个给出整个集合，另一个只是每个元素的个别信息。

我做错了什么？

const PirateBay = require ('thepiratebay');
var os = require ('os');
var sys = require('util');
var util = require('util');
var cfg = require('./config/appconf.js');
var mysql = require('mysql');
var Torrent = require('./models/torrent.js');
var parseTorrent = require('parse-torrent')

var async = require('async');
function saveResults (results) {
    console.log( "Save Results");
    var cTorrents = [];
    for (var key in results) {
        var t =results[key];
        var torrent = new Torrent()
        torrent.id = t.id;
        torrent.name =  t.name;
        torrent.size = t.size;
        torrent.seeders = t.seeders;
        torrent.leechers = t.leechers;
        torrent.verified = t.verified;
        torrent.uploader = t.uploader;
        torrent.category = t.category.name;
        torrent.description = t.description;
        torrent.subcategory = t.subcategory.name;
        var r = parseTorrent (t.magnetLink);
        torrent.announce = r.announce;
        torrent.hash = r.infoHash;
        cTorrents.push (torrent);
    }
    return cTorrents;
}
PirateBay
    .recentTorrents()
    .then( function(results){
         var lTorrents = saveResults(results);

         async.each (lTorrents,function (t,next){
                await PirateBay
                    .getTorrent(t.id)
                    .then(function (err, doc){
                        console.log(doc.description);
                        t.doc = doc.description;
                        next();
                    });
         },function (err) {
            console.log ("WHNEEEEE");
            console.log(lTorrents);
         });
         console.log(lTorrents);
    })
    .catch (function (err){
        console.log(err);
    });

Answer 1

您不需要异步模块，Promise就足够了。特别是你可能感兴趣的是Promise.all()，它接受一系列Promise并在所有promises完成时解析。使用Array.prototype.map() lTorrents的每个元素都可以映射到Promise中。这是一个例子..

PirateBay
        .recentTorrents()
        .then(function(results){
             var lTorrents = saveResults(results);
             return Promise.all(lTorrents.map(function(t) {
                 return PirateBay.getTorrent(t.id)
                     .then(function(doc) {
                         t.doc = doc.description;
                         return t;
                     })
                     .catch(function(err) {
                         // if one request fails, the whole Promise.all() rejects, 
                         // so we can catch ones that fail and do something instead...
                         t.doc = "Unavailable (because getTorrent failed)";
                         return t;
                     });
             }));
        })
        .then(function(lTorrents) {
            // do what you gota do..
        })

Node.js在另一个语句

1 个答案: