Node.js文件上传（Express 4，MongoDB，GridFS，GridFS-Stream）

Question

我试图在我的node.js应用程序中设置文件API。我的目标是能够直接将文件流写入gridfs，而无需最初将文件存储到磁盘。似乎我的创建代码正在运行。我能够将文件上传保存到gridfs。问题是正在读取文件。当我尝试通过Web浏览器窗口下载保存的文件时，看到文件内容包裹着以下内容：

------WebKitFormBoundarye38W9pfG1wiA100l
Content-Disposition: form-data; name="file"; filename="myfile.txt"
Content-Type: text/javascript

***File contents here***

------WebKitFormBoundarye38W9pfG1wiA100l--

所以我的问题是，在将文件保存到gridfs之前，我该怎么做才能从文件流中剥离边界信息？这是我正在使用的代码：

'use strict';

var mongoose = require('mongoose');
var _ = require('lodash');

var Grid = require('gridfs-stream');
Grid.mongo = mongoose.mongo;
var gfs = new Grid(mongoose.connection.db);

// I think this works. I see the file record in fs.files
exports.create = function(req, res) {
    var fileId = new mongoose.Types.ObjectId();

    var writeStream = gfs.createWriteStream({
        _id: fileId,
        filename: req.query.name,
        mode: 'w',
        content_type: req.query.type,
        metadata: {
            uploadedBy: req.user._id,
        }
    });

    writeStream.on('finish', function() {
        return res.status(200).send({
            message: fileId.toString()
        });
    });

    req.pipe(writeStream);
};

// File data is returned, but it's wrapped with
// WebKitFormBoundary and has headers.
exports.read = function(req, res) {
    gfs.findOne({ _id: req.params.id }, function (err, file) {
        if (err) return res.status(400).send(err);

        // With this commented out, my browser will prompt
        // me to download the raw file where I can see the
        // webkit boundary and request headers
        //res.writeHead(200, { 'Content-Type': file.contentType });

        var readstream = gfs.createReadStream({
            _id: req.params.id
            // I also tried this way:
            //_id: file._id
        });

        readstream.pipe(res);
    });
};

顺便说一句，我目前没有为这些路由使用任何中间件，但愿意这样做。我只是不希望文件在发送到gridfs之前先打入磁盘。

编辑：

对于每个@fardjad，我添加了用于多部分/表单数据解析的node-
multiparty
模块，并且这种方法可行。但是，当我下载一个上传的文件并与原始文件（以文本形式）进行比较时，编码存在很多差异，并且下载的文件将无法打开。这是我最近的尝试。

'use strict';

var mongoose = require('mongoose');
var _ = require('lodash');
var multiparty = require('multiparty');
var Grid = require('gridfs-stream');
Grid.mongo = mongoose.mongo;
var gfs = new Grid(mongoose.connection.db);

exports.create = function(req, res) {
    var form = new multiparty.Form();
    var fileId = new mongoose.Types.ObjectId();

    form.on('error', function(err) {
      console.log('Error parsing form: ' + err.stack);
    });

    form.on('part', function(part) {
        if (part.filename) {
            var writeStream = gfs.createWriteStream({
                _id: fileId,
                filename: part.filename,
                mode: 'w',
                content_type: part.headers['content-type'],
                metadata: {
                    uploadedBy: req.user._id,
                }
            })

            part.pipe(writeStream);
        }
    });

    // Close emitted after form parsed
    form.on('close', function() {
        return res.status(200).send({
            message: fileId.toString()
        });
    });

    // Parse req
    form.parse(req);
};

exports.read = function(req, res) {
    gfs.findOne({ _id: req.params.id }, function (err, file) {
        if (err) return res.status(400).send(err);

        res.writeHead(200, { 'Content-Type': file.contentType });

        var readstream = gfs.createReadStream({
            _id: req.params.id
        });

        readstream.pipe(res);
    });
};

最终编辑：

这是我从另一个开发人员复制并修改的简单实现。这对我有用：（我仍在尝试弄清楚为什么它在我的原始Express应用程序中不起作用。似乎有些干扰）

https://gist.github.com/pos1tron/094ac862c9d116096572

var Busboy = require('busboy'); // 0.2.9
var express = require('express'); // 4.12.3
var mongo = require('mongodb'); // 2.0.31
var Grid = require('gridfs-stream'); // 1.1.1"
var app = express();
var server = app.listen(9002);

var db = new mongo.Db('test', new mongo.Server('127.0.0.1', 27017));
var gfs;
db.open(function(err, db) {
  if (err) throw err;
  gfs = Grid(db, mongo);
});

app.post('/file', function(req, res) {
  var busboy = new Busboy({ headers : req.headers });
  var fileId = new mongo.ObjectId();

  busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {
    console.log('got file', filename, mimetype, encoding);
    var writeStream = gfs.createWriteStream({
      _id: fileId,
      filename: filename,
      mode: 'w',
      content_type: mimetype,
    });
    file.pipe(writeStream);
  }).on('finish', function() {
    // show a link to the uploaded file
    res.writeHead(200, {'content-type': 'text/html'});
    res.end('<a href="/file/' + fileId.toString() + '">download file</a>');
  });

  req.pipe(busboy);
});

app.get('/', function(req, res) {
  // show a file upload form
  res.writeHead(200, {'content-type': 'text/html'});
  res.end(
    '<form action="/file" enctype="multipart/form-data" method="post">'+
    '<input type="file" name="file"><br>'+
    '<input type="submit" value="Upload">'+
    '</form>'
  );
});

app.get('/file/:id', function(req, res) {
  gfs.findOne({ _id: req.params.id }, function (err, file) {
    if (err) return res.status(400).send(err);
    if (!file) return res.status(404).send('');

    res.set('Content-Type', file.contentType);
    res.set('Content-Disposition', 'attachment; filename="' + file.filename + '"');

    var readstream = gfs.createReadStream({
      _id: file._id
    });

    readstream.on("error", function(err) {
      console.log("Got error while processing stream " + err.message);
      res.end();
    });

    readstream.pipe(res);
  });
});

Answer 1

请参阅我对您在github上创建的问题的评论。我遇到了同样的问题，但是我设法调试了该问题。我将其范围缩小到我确信问题出在某个快速中间件修改了请求的位置。我一一禁用了中间件，直到发现了不太可能的罪魁祸首：connect-
livereload

我注释掉了app.use（require（’connect-livereload’）（））;
问题就解决了。我相信它是将livereload脚本注入响应（一个二进制图像文件）中。