Busboy 在读取文件长度和文件数据之前发回响应？我正在上传单个文件

Question

module.exports.upload = function (req, res) {
  fileName = path.basename(req.query.fileName);
  var fileExtn = path.extname(req.query.fileName);
  console.log("fileName " + fileName);
  console.log("fileExtn " + fileExtn);

  var fileCheckResponse = FileCheck(req, res);  // FileCheck method containing Busboy code
  console.log("file check response =" + fileCheckResponse);
}

function FileCheck(req, res) {
var dataSize;
  var busboy = new Busboy({ headers: req.headers });
    busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
      file.on("data", function (data) {
        dataSize=data.length;
      console.log("File [" + fieldname + "] got " + data.length + " bytes");
      console.log("the upload file data ===== " + data);

      })
    });
    busboy.on('finish', function() {
      console.log('Upload complete');
      return dataSize;
    });
   return  req.pipe(busboy);
}`

我在上传方法中调用 FileCheck 函数，其中存在 Busboy 代码，我首先调试并检查 FileCheck 函数，它到达行 ( busboy.on('file', function(fieldname, file, filename, encoding, mimetype) ）然后它不会进入它进入另一行（ busboy.on('finish', function()) 然后响应对象返回到上传方法，我期待数据长度在 fileCheckResponse 中但获取不包含它的对象，再次继续调试它返回到 FileCheck 函数，这次它命中（file.on（"data"，函数（数据））并在控制台上打印数据正如我所写，但响应不会返回到上传方法。

我的问题和目标又是获取数据长度作为响应，但现在我第一次获取对象作为响应，第二次指针没有返回到上传方法。

Answer 1

// try using const or let instead of var

module.exports.upload = function (req, res) {

  fileName = path.basename(req.query.fileName);
  const fileExtn = path.extname(req.query.fileName)
  console.log("fileName " + fileName);
  console.log("fileExtn " + fileExtn);


  // try to make FileCheck function synchronous using promise or async await

  FileCheck(req, res)
    .then(fileSize => {
        console.log(fileSize, 'fileSize')
        // send whatever response you need
    })
}

function FileCheck(req, res) {
    return new Promise((resolve, reject) => {
        let dataSize;
        let busboy = new Busboy({ headers: req.headers });
        busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
            file.on('data', function (data) {
                dataSize = data.length;
                console.log("File [" + fieldname + "] got " + data.length + " bytes");
            })
        });
        busboy.on('finish', function() {
            console.log('Upload complete');
            resolve(dataSize)
        });
        req.pipe(busboy)
    })
}

Busboy 在读取文件长度和文件数据之前发回响应？我正在上传单个文件

Busboy sending response back before reading file length and file data? i am uploading single file

multipartform-data

file-read

node.js

busboy

nodejs-server