node.js - 无法读取未定义的属性名称

Question

我是 Node.js 新手。我从昨天开始学习。

我有一个带有简单文件上传和提交按钮的表单

JS文件

var http = require('http');
var fs = require('fs');
var formidable = require('formidable');

http.createServer(function(req, res){

    if (req.url == '/fileupload'){
       var form = new formidable.IncomingForm();
       form.parse(req, function (err, files, fields){
           var oldpath = files.filetoupload.path;
           console.log(oldpath);
           var newpath = 'F:/' + files.filestoupload.name;
           console.log('Destination set!');
           fs.readFile(oldpath, function (err, data){
               if (err) throw err;
               console.log('File read!');
               fs.writeFile(newpath, data, function(err){
                   if (err) throw err;
                   res.write('Package shipped and moved');
                   res.end();
                   console.log('Newpath is' + newpath);
                   });
                fs.unlink(oldpath, function (err){
                    if (err) throw err;
                    console.log("Temp file deleted");
                    });
               });
           });
    } else {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write('<form action="fileupload" method="post">');
    res.write('<input type="file" name="filetoupload"><br><br>');
    res.write('<input type="submit" name="submit" value="submit">');
    res.write('</form>');
    return res.end();
    }
}).listen(8080);

它以某种方式在浏览器上运行，但是当我点击上传按钮时，命令提示符中会弹出错误

TypeError: Cannot read property 'name' of undefined
    at F:\Prince\workspace\NODE JS\formidable.js:12:48
    at IncomingForm.<anonymous> (F:\Prince\workspace\NODE JS\node_modules\formidable\lib\incoming_form.js:107:9)
    at IncomingForm.emit (events.js:182:13)
    at IncomingForm._maybeEnd (F:\Prince\workspace\NODE JS\node_modules\formidable\lib\incoming_form.js:557:8)
    at QuerystringParser.parser.onEnd (F:\Prince\workspace\NODE JS\node_modules\formidable\lib\incoming_form.js:458:10)
    at QuerystringParser.end (F:\Prince\workspace\NODE JS\node_modules\formidable\lib\querystring_parser.js:25:8)
    at IncomingMessage.<anonymous> (F:\Prince\workspace\NODE JS\node_modules\formidable\lib\incoming_form.js:132:30)
    at IncomingMessage.emit (events.js:182:13)
    at endReadableNT (_stream_readable.js:1098:12)
    at process.internalTickCallback (internal/process/next_tick.js:72:19)

如果有人澄清我的错误，我将不胜感激。

PS:也请阅读评论。

Answer 1

经过一段时间的调试，我发现了这里的问题。

这里有三个错误。

正如@Jordan S所说，第12行有一个拼写错误

filestoupload 应为 filestoupload

然后第10行表单解析中的回调格式不正确

form.parse(req, function (err, files, fields) 到 form.parse(req, function (err, fields, files)

最后一个的形式是 enctype 缺失

res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');

添加 enctype="multipart/form-data" 修复了最终问题。

但是我还是不知道添加enctype有什么意义

更新了 JS 文件

var http = require('http');
var fs = require('fs');
var formidable = require('formidable');

http.createServer(function(req, res){
    if (req.url == '/fileupload'){
       var form = new formidable.IncomingForm();
       form.parse(req, function (err, fields, files){
           var oldpath = files.filetoupload.path;
           console.log(oldpath);
           var newpath = 'F:/' + files.filetoupload.name;
           console.log('Destination set!');
           fs.readFile(oldpath, function (err, data){
               if (err) throw err;
               console.log('File read!');
               fs.writeFile(newpath, data, function(err){
                   if (err) throw err;
                   res.write('Package shipped and moved');
                   res.end();
                   console.log('Newpath is' + newpath);
                   });
                fs.unlink(oldpath, function (err){
                    if (err) throw err;
                    console.log("Temp file deleted");
                    });
               });
           });
    } else {
    res.writeHead(200, {'Content-Type': 'text/html'});
    res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');
    res.write('<input type="file" name="filetoupload"><br><br>');
    res.write('<input type="submit" name="submit" value="submit">');
    res.write('</form>');
    return res.end();
    }
}).listen(8080);