承诺抛出未处理的错误的解决
我有下面的代码，但是当parsing被调用时，它抛出：
Possibly unhandled Error: undefined at Promise$_rejecter (c:\projects\Test\promiseftp\node_modules\bluebird\js\main\promise.js:602:58) at WriteStream.<anonymous> (c:\projects\Test\promiseftp\index.js:45:33) at WriteStream.EventEmitter.emit (events.js:117:20) at fs.js:1598:14 at Object.oncomplete (fs.js:107:15) 代码如下：
var Client = require('ftp'); var path = require('path'); var fs = require('fs'); var Promise = require('bluebird'); var c = new Client(); var connectionProperties = { host: "myhost", user: "myuser", password: "mypwd" }; c.connect(connectionProperties); var downloadFiles = new Promise.method(function () { return new Promise(function (reject, resolve) { c.on('ready', function () { c.list(function (err, list) { if (err) reject(err); list.forEach(function (element, index, array) { //Ignore directories if (element.type === 'd') { console.log('ignoring directory ' + element.name); return; } //Ignore non zips if (path.extname(element.name) !== '.zip') { console.log('ignoring file ' + element.name); return; } c.get(element.name, function (err, stream) { if (err) reject(err); console.log(element.name); stream.once('close', function () { //c.end(); //resolve(); }); var pipeaction = stream.pipe(fs.createWriteStream(element.name)); pipeaction.on('close', function () { console.log('close'); //THROWS HERE! resolve(); }); }); }); }); }); }); }); downloadFiles().then(function () { console.log('woot'); });
任何想法为什么？
请不要混合使用callback和承诺，看看它有多简单：
when(c, "ready").then(function(){ return c.listAsync(); }).filter(function(element) { return element.type !== "d" && path.extname(element.name) === ".zip"; }).map(function(element) { return c.getAsync(element.name).then(function(stream) { return when(stream.pipe(fs.createWriteStream(element.name)), "close"); }) }).then(function(){ console.log("all files copied"); });
样板：
var path = require('path'); var fs = require('fs'); var Promise = require('bluebird'); var Client = require('ftp'); Promise.promisifyAll(Client.prototype); var c = new Client(); var connectionProperties = { host: "myhost", user: "myuser", password: "mypwd" }; c.connect(connectionProperties); function when(obj, event) { return new Promise(function(resolve) { obj.on(event, resolve); }); }