request-promise未处理的拒绝RequestError：错误：ETIMEDOUT

Question

嗨我尝试通过承诺请求写一些下载功能，但如果我有超时我无法处理此错误，我尝试meny示例但仍然有此错误

Unhandled rejection RequestError: Error: ETIMEDOUT
    at new RequestError (/home/parse/node_modules/request-promise-core/lib/errors.js:14:15)
    at Request.plumbing.callback (/home/parse/node_modules/request-promise-core/lib/plumbing.js:87:29)
    at Request.RP$callback [as _callback] (/home/parse/node_modules/request-promise-core/lib/plumbing.js:46:31)
    at self.callback (/home/parse/node_modules/request/request.js:186:22)
    at emitOne (events.js:101:20)
    at Request.emit (events.js:191:7)
    at Timeout._onTimeout (/home/parse/node_modules/request/request.js:816:16)
    at ontimeout (timers.js:380:14)
    at tryOnTimeout (timers.js:244:5)
    at Timer.listOnTimeout (timers.js:214:5)

我的代码

下载功能：

function downloadPhoto(url,uploadUrl,name){
   return new Promise(function(resolve, reject){
        rp(url,{timeout:15000},function(e){if(e) reject(e);}).on('error', function(e){return reject(e);}).pipe(fs.createWriteStream(name+'.jpg')).on('finish', () => {
        //console.log('done Download photo');
         return resolve();
    });
  });

}

叫这个功能

function sndPht(url,uploadUrl){
    return new Promise(function(resolve, reject){
      return downloadPhoto(url,uploadUrl,name).then(function(){
             ..... some logic .....  
        }).catch(function(err){
            return reject(err);
        });
}

对于许多文件我在bluebird js map中调用函数：

Promise.map(photos, function(photo) {
  if(photo.type === 'photo'){
    return sndPht(photo,uploadUrl);
  }  
},{concurrency: 1});

我做错了什么？

Answer 1

我有一个解决方案，如果你使用一个请求 - 承诺你大喊创建承诺并返回他并抓住它的例子，它不管用我的情况下的管道，所以我们需要改变功能下载像

function downloadPhoto(url){
  var options = {
      uri:url,
      timeout:10000,
      encoding: 'binary'
  };

  return rp(options);
}

然后我们可以像使用它一样

return downloadPhoto(url).then(function(file){
      fs.writeFileSync(name+'.jpg', file, 'binary');
    }).catch(function(err){
     console.log(err);
});

我们可以使用地图

Promise.map(photos, function(photo) {
  if(photo.type === 'photo'){
    return sndPht(photo,uploadUrl);
  }  
},{concurrency: 1});

但如果你需要downlod大文件，你需要使用calback的请求

Answer 2

您可以使用Promise.race来使用解析或拒绝的第一个promise的值。

使用这种技术，如果下载时间过长，我们可能会在一段时间后发生错误。 downloadPhoto Promise仍将解决，但不会被处理

 const images = [ { url: 'www.foo.com', uploadUrl: '/foo', name: 'foo' } , { url: 'www.bar.com', uploadUrl: '/bar', name: 'bar' } , { url: 'www.baz.com', uploadUrl: '/baz', name: 'baz' } ] const promiseTimeout = (delay, promise) => Promise.race([ new Promise((resolve, reject) => setTimeout(resolve, delay, { status: 'error', msg: 'took too long!' }) ), promise ]) const downloadPhoto = ({ url, uploadUrl, name }) => promiseTimeout( 1000, new Promise((resolve, reject) => { setTimeout(resolve, 3000, { status: 'success', msg: `this will never resolve ${url}` }) }) ) // map images array [...image] into [...Promise(image)] const imagePromises = images.map(downloadPhoto) // resolve all promises Promise.all(imagePromises) // called once all promises are resolved with array of results .then(images => { // map over the resolved images and do further processing images.map(console.log.bind(console, 'Image resolved')) }) // promises no longer reject, you will need to look at the status .catch(console.log.bind(console, 'Error: '))