使用 NodeJS 和 node-fetch 代理多部分表单数据

如何解决使用 NodeJS 和 node-fetch 代理多部分表单数据

如何将传入的 NodeJS/Express 请求 (req) 对象转换为可以在代理请求中发送的对象？

我的 NodeJS/express 服务使用 node-fetch 将请求代理到单独的服务器。传入的 curl 请求如下所示（Firefox POSIX curl）

curl 'https://localhost:8080/bluecost/spreadsheet/upload/SSCSpreadsheetUpload-09192020.xlsx' -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:85.0) Gecko/20100101 Firefox/85.0' -H 'Accept: application/json,text/plain,*/*' -H 'Accept-Language: en-US,en;q=0.5' --compressed -H 'Content-Type: multipart/form-data; boundary=---------------------------37552304939101372432093632492' -H 'Origin: https://localhost:8080' -H 'DNT: 1' -H 'Connection: keep-alive' -H 'Referer: https://localhost:8080/spreadsheet-upload' -H 'Cookie: connect.sid=s%3ARxnRck1VzcCXk05LKV1CJ5PeslCK1sWC.WqqK%2B0CHsAP0MpcFzRFbHTh19YOoeBi0mIAKCPQ%2BSGU; access_token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJzcHJpbnQtbWlkZGxld2FyZS1pc3N1ZXIiLCJzdWIiOiJCZW4uUHJhY2h0MUBpYm0uY29tIiwibm90ZXNJZCI6IkJlbiBQcmFjaHQiLCJzZXJpYWxOdW0iOiI4Njc1NTU4OTciLCJleHAiOjE2MTQ4MjgwNzksImJsdWVHcm91cHMiOlsiQkxVRUNPU1RfU1BSRUFEU0hFRVRfVVBMT0FEX1RFU1QiXSwiaWF0IjoxNjE0ODIwODk3fQ.jWhvsHZiJLRvAHG7SDTmOkdcpMRHxiaLUWDhfJmRXv0' -H 'Pragma: no-cache' -H 'Cache-Control: no-cache' --data-binary $'-----------------------------37552304939101372432093632492\r\nContent-Disposition: form-data; name="file"; filename="SSCSpreadsheetUpload-09192020.xlsx"\r\nContent-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet\r\n\r\n-----------------------------37552304939101372432093632492--\r\n'

路由的简化版本如下所示：

app.use('/multipart',(req,res,next) => {
            const URL = require('url').URL;
            var spreadsheet_client_url = new URL(config.spreadsheet_client_host);
            spreadsheet_client_url.pathname = req.originalUrl;
            // spreadsheet_client_url.pathname = spreadsheet_client_url.pathname.replace('/spreadsheet-upload','/');
            logger.debug('/spreadsheet-upload: Generating token based on proxyReqOpts.user=' + req.user);

            logger.info(`@@Request ${req.method} ${spreadsheet_client_url.href}`);
            var accessToken = generateToken(req.user);
            /**
             * Set bearer token based on code from Sprint-API's lua code
             */
            // req.setHeader('Authorization','Bearer ' + accessToken);
            logger.debug('Route: /spreadsheet-upload: adding Authorization: Bearer ' + accessToken);
            var newHeaders = req.headers;
            newHeaders['Authorization'] = 'Bearer ' + accessToken;
            if (isMultipartRequest(req)) {
                newHeaders['Content-Length'] = req.body.length;
                // build a string in multipart/form-data format with the data you need
                const formdataUser =
                    `--${request.headers['content-type'].replace(/^.*boundary=(.*)$/,'$1')}\r\n` +
                    `Content-Disposition: form-data; name="reqUser"\r\n` +
                    `\r\n` +
                    `${JSON.stringify(req.user)}\r\n`

            } else {

                const options = {
                    port: spreadsheet_client_url.port,path: spreadsheet_client_url.pathname,body: req.body,method: req.method,headers: newHeaders,redirect: true
                };
                console.log('@@@');
                console.log('@@@ url: ' + spreadsheet_client_url.href + 'post-options: ' + JSON.stringify(options));
                console.log('@@@');
                const fetch = require('node-fetch');
                fetch(spreadsheet_client_url,options).then(r => {
                    console.log('@@ reached fetch result retrieved');
                    return r.text();
                }).then(fetchText => {
                    console.log('@@ reached fetch text result retrieved');
                    /*
                    // This code complains that headders can't be set after sending to client
                    res.writeHead(res.statusCode,res.headers);
                    res.send(fetchText);
                    */
                    // res.body=fetchText;
                    res.status(200).send(fetchText);

                    next();
                }
            }

            )
        .catch(err => { console.log('Error fetching ' + err) });
})

function isMultipartRequest(req) {
    let contentTypeHeader = req.headers['content-type'];
    return contentTypeHeader && contentTypeHeader.indexOf('multipart') > -1;
}

所以我有一个传入请求，我相信我可以可靠地区分普通请求和多部分请求。许多例子建议创建这个“表单数据”对象，然后像这样发送它：

const FormData = require('form-data');     
const form = new FormData();

const buffer = // e.g. `fs.readFileSync('./fileLocation');
const fileName = 'test.txt';

form.append('file',buffer,{
  contentType: 'text/plain',name: 'file',filename: fileName,});

fetch('https://httpbin.org/post',{ method: 'POST',body: form })
    .then(res => res.json())
    .then(json => console.log(json));

我想继续使用 node-fetch 因为它是我最了解的魔鬼。我应该使用表单数据对象并像上面一样传递它吗？有没有更好的办法？我想知道如何从请求对象构建表单数据对象，因为我只知道它是多部分的，仅此而已。

最终目标是一个 Java Spring-Boot 服务器，它接受一个 MultipartFile 文件，如下所示：

    @PostMapping("/spreadsheet/upload/{filename}")
    public ResponseEntity<HashMap<String,Object>> uploadSpreadsheet(@RequestBody MultipartFile file,@PathVariable("filename") String filename) {

对于普通的非多部分表单请求，它足以匹配到此方法，但“文件”对象为空。