Node.js使用request模块从url下载图片时出现URI错误。

Question

我正在循环下载图片，当我把循环设置为 for (var i = 0; i < 100; i++) { 我下载图片没有问题，但只要我改变我的 i 范围要超过99（含100），所以任何类似。for (var i = 100; i < 200; i++) { OR for (var i = 0; i < 200; i++) { 我得到一个错误。这是我的代码。

var fs = require('fs');

var request = require('request');

var download = function(uri, filename, callback){
  request.head(uri, function(err, res, body){
    request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
  });
};

var arrLength = allProducts.length;

for (var i = 0; i < arrLength; i++) { 

    let imgName = allProducts[i].code;    
    let imgUrl = allProducts[i].nofrillsImgLink    

    download(`${imgUrl}`, `./allProductsImg/${imgName}.png`, function(){              
      });
};

这是我得到的错误：

events.js:287
      throw er; // Unhandled 'error' event
      ^

Error: Invalid URI "undefined"
    at Request.init (.../node_modules/request/request.js:273:31)
    at new Request (.../node_modules/request/request.js:127:8)
    at request (.../node_modules/request/index.js:53:10)
    at Request._callback (.../downloadImg.js:7:5)
    at self.callback (.../node_modules/request/request.js:185:22)
    at Request.emit (events.js:310:20)
    at Request.init (.../node_modules/request/request.js:273:17)
    at new Request (.../node_modules/request/request.js:127:8)
    at request (.../node_modules/request/index.js:53:10)
    at Function.head (.../node_modules/request/index.js:61:12)
Emitted 'error' event on Request instance at:
    at Request.init (.../node_modules/request/request.js:273:17)
    at new Request (.../node_modules/request/request.js:127:8)
    [... lines matching original stack trace ...]
    at Function.head (.../node_modules/request/index.js:61:12)

Answer 1

你能把这段代码从

var download = function(uri, filename, callback){
  request.head(uri, function(err, res, body){
    request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
  });
};

到

var download = function(uri, filename, callback){
  if(uri !== undefined){
    request.head(uri, function(err, res, body){
      request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
    });
  }
};

Answer 2

把代码改成这样，就成功了。

for (var i = 0; i < 11952; i++) { 

    let imgName = allProducts[i].code;    
    let imgUrl = allProducts[i].nofrillsImgLink    

      request({
        url : `${imgUrl}`,
        //make the returned body a Buffer
        encoding : null
    }, function(error, response, body) {

        //will be true, body is Buffer( http://nodejs.org/api/buffer.html )
        console.log(body instanceof Buffer);

        //do what you want with body
        //like writing the buffer to a file
        fs.writeFile(`./allProductsImg/${imgName}.png`, body, {
            encoding : null
        }, function(err) {

            if (err)
                throw err;
            console.log('It\'s saved!');
        });

    });

};