request-promise未處理的拒絕RequestError：錯誤：ETIMEDOUT

Question

嗨我嘗試通過承諾請求寫一些下載功能，但如果我有超時我無法處理此錯誤，我嘗試meny示例但仍然有此錯誤

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)

我的代碼

下載功能：

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();
    });
  });

}

叫這個功能

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);
        });
}

對於許多文件我在bluebird js map中調用函數：

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

我做錯了什么？

Answer 1

我有一個解決方案，如果你使用一個請求 - 承諾你大喊創建承諾並返回他並抓住它的例子，它不管用我的情況下的管道，所以我們需要改變功能下載像

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

  return rp(options);
}

然后我們可以像使用它一樣

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

我們可以使用地圖

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的請求

Answer 2

您可以使用Promise.race來使用解析或拒絕的第一個promise的值。

使用這種技術，如果下載時間過長，我們可能會在一段時間后發生錯誤。 downloadPhoto Promise仍將解決，但不會被處理

 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: '))