req.files.upload.length返回文件计数为零，或上传多个文件，当一个文件上传时，它返回文件大小

In this loop, “req.files.upload.length” returns file count when 0, or more than one files are uploaded, however when one file is uploaded “req.files.upload.length” returns file size. Why?

在此循环中，“req.files.upload.length”在0或多个文件上载时返回文件计数，但是当上载一个文件时，“req.files.upload.length”返回文件大小。为什么？

upload handler:

上传处理程序

app.post('/upload', function(req, res){
    console.log('file count: ' + req.files.upload.length);
    var file;
    var i = 0;
    for(var x = 0; x < req.files.upload.length; x++){
        file = req.files.upload[x];
        console.log(file.name + ' (' + (file.size * 0.0009765625).toFixed(0) + ' kB, ' + file.type + ')');
    };
    console.log(req.files.upload.length + ' files uploaded to server');
    res.redirect('/forms');
});

When I upload one file I get this error:

当我上传一个文件时，我收到此错误：

TypeError: Cannot read property 'name' of undefined
    at /Users/frode/Dropbox/Nettsider/expressmal/app.js:296:20
    at callbacks (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:272:11)
    at param (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:246:11)
    at pass (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:253:5)
    at Router._dispatch (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:280:4)
    at Object.handle (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:45:10)
    at Context.next (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/node_modules/connect/lib/http.js:204:15)
    at Context.<anonymous> (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/passport/lib/passport/context/http/actions.js:64:8)
    at SessionStrategy.pass (native)
    at /Users/frode/Dropbox/Nettsider/expressmal/node_modules/passport/lib/passport/strategies/session.js:48:12
URIError: URI malformed
    at /Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/node_modules/connect/lib/middleware/static.js:119:14
    at Object.static [as handle] (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/node_modules/connect/lib/middleware/static.js:60:5)
    at next (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/node_modules/connect/lib/http.js:204:15)
    at pass (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:219:24)
    at Router._dispatch (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:280:4)
    at Object.handle (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/lib/router/index.js:45:10)
    at Context.next (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/express/node_modules/connect/lib/http.js:204:15)
    at Context.<anonymous> (/Users/frode/Dropbox/Nettsider/expressmal/node_modules/passport/lib/passport/context/http/actions.js:64:8)
    at SessionStrategy.pass (native)
    at /Users/frode/Dropbox/Nettsider/expressmal/node_modules/passport/lib/passport/strategies/session.js:48:12

1 个解决方案

#1

In Express/Connect, req.files will be an object with the input[type=file] name attribute as key, and the content as the value. If there are more than one input[type=file] with the same name, it will be an array instead. If you control the view, i.e. the web page with the form, you should be able to have either unique names for each file input, or know that you have more than one with the name "upload".

在Express / Connect中，req.files将是一个对象，其输入[type = file] name属性为键，内容为值。如果有多个输入[type = file]具有相同的名称，则它将是一个数组。如果您控制视图，即带有表单的网页，您应该能够为每个文件输入设置唯一的名称，或者知道您有多个名称为“upload”的名称。

Update: I didn't think of the most obvious case, where the user has selected more than one file.

更新：我没有想到最明显的情况，用户选择了多个文件。

Update: Here's what req.files will look like for two different cases:

更新：以下是两种不同情况下req.files的样子：

One file:

一个文件：

req.files = {
  upload: {
    name: 'foo.txt'
    length: 1024
  }
}

Two files:

两个文件：

req.files = {
  upload: [
    {
      name: 'foo.txt'
      length: 1024
    },
    {
      name: 'bar.txt'
      length: 2048
    }
  ]
}

As should be clear from this example, req.files.upload will have a length property in either case, but as you have found out they mean different things.

从这个例子中可以清楚地看出，req.files.upload在任何一种情况下都会有一个length属性，但是你发现它们意味着不同的东西。

You probably want to iterate over an array in any case, to simplify your own code. This is easy to accomplish with [].concat:

您可能希望在任何情况下迭代数组，以简化您自己的代码。使用[] .concat很容易实现：

// Make sure that files is always an array
var files = [].concat(req.files.upload);
for(var x = 0; x < files.length; x++){
    file = files[x];
    // ...
}

1 个解决方案

#1

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