我有一段代码：

router.route("/post")
        .get(function(req, res) {
            ...
        })
        .post(authReq, function(req, res) {
            ...
            // Get uploaded file
            var fstream
            req.pipe(req.busboy)
            req.busboy.on('file', function (fieldname, file, filename, encoding, mimetype) {
            ...

            var fileSuffix = mimetype.split("/")[1] // Get suffix, may not always be correct
            var tmpFileName = postCount + "." + fileSuffix
            var tmpFileURL = __dirname + "/tmp/" + tmpFileName
            // Start writing
            fstream = fs.createWriteStream(tmpFileURL)
            file.pipe(fstream)
            fstream.on('close', function() {
                 ...
            })
        })
    })
})

这个使用完美地工作。然而，我不知道发生了什么，但我今天拿起我的电脑，发现每次我试图发帖时都会发生这个错误：

TypeError: Cannot call method 'on' of undefined
    at IncomingMessage.Readable.pipe (_stream_readable.js:494:8)
    at /Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/apiRoutes.js:139:8
    at Layer.handle [as handle_request] (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/layer.js:82:5)
    at next (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/route.js:100:13)
    at authReq (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/apiRoutes.js:17:3)
    at Layer.handle [as handle_request] (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/layer.js:82:5)
    at next (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/route.js:100:13)
    at next (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/route.js:94:14)
    at Route.dispatch (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/route.js:81:3)
    at Layer.handle [as handle_request] (/Users/nathan/Library/Mobile Documents/com~apple~CloudDocs/Dev/LaughItUp/Code/Server/node_modules/express/lib/router/layer.js:82:5)

_stream_readable.js:501
    dest.end();
         ^
TypeError: Cannot call method 'end' of undefined
    at IncomingMessage.onend (_stream_readable.js:501:10)
    at IncomingMessage.g (events.js:180:16)
    at IncomingMessage.emit (events.js:92:17)
    at _stream_readable.js:943:16
    at process._tickCallback (node.js:419:13)

在我的index.js文件中，我有以下代码来使用Busboy：

app.use(busboy())

然后这段代码包含我的路线：

app.use("/api", require("./apiRoutes.js")())

先谢谢你了！

**编辑：**我做了更多的调试，我想我找到了问题。req.busboy未定义。所以我去查了源代码。下面是connect-busboy模块中的一些代码：

if (req.busboy
|| req.method === 'GET'
|| req.method === 'HEAD'
|| !hasBody(req)
|| !RE_MIME.test(mime(req)))
return next()

当我打印出实际值时，busboy不存在，请求方法是'POST'，hasBody(req)结果为true，而RE_MIME.test(mime(req)))结果为false，这就是为什么busboy没有添加到请求中。
我的示例文件的MIME类型是image/gif。下面是正则表达式connect-busboy测试image/gif关闭（又名RE_MIME变量）：

/^(?:multipart\/.+)|(?:application\/x-www-form-urlencoded)$/i;

因此，我得出结论，我误解了API。Busboy是否只支持HTML表单？

**编辑#2：**我只是切换到Multer，它工作正常。然而，我相信我的问题是，我需要把文件放在一个多部分的请求;我不知道为什么它以前是工作的。谢谢！