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

Question

我正在尝试在我的 node.js 应用程序中设置一个文件 API。我的目标是能够将文件流直接写入 gridfs，而无需最初将文件存储到磁盘。看来我的创建代码正在运行。我能够保存文件上传到 gridfs。问题是读取文件。当我尝试通过网络浏览器下载已保存的文件时 window，我看到文件内容被如下内容包裹：

------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，在将文件流保存到 gridfs 之前，我需要做什么来去除文件流中的边界信息？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，但我愿意这样做。我只是不想让文件在发送到 gridfs 之前先进入磁盘。

编辑：

Per @fardjad，我为 multipart/form-data 解析添加了 node-multiparty 模块，它有点工作。但是当我下载上传的文件并与原始文件（如文本）进行比较时，编码存在很多差异，并且下载的文件无法打开。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：

这是我从其他开发人员那里复制并修改的一个简单实现。这对我有用：（我仍在尝试弄清楚为什么它在我原来的 express 应用程序中不起作用。似乎有什么干扰）

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

看起来文件是通过 HTML 形式上传的，在这种情况下，您需要解码 multipart/form-data encoded data, re-assemble the parts if needed and save the file to GridFS. For parsing, you can use something like node-multiparty.

Answer 2

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，但我设法调试了这个问题。我将范围缩小到我确信问题出在一个快速中间件修改了请求的地方。我一个一个地禁用了我的中间件，直到我发现不太可能的罪魁祸首：connect-livereload

我注释掉了app.use(require('connect-livereload')());问题就消失了。我相信它是将 livereload 脚本注入到响应（二进制图像文件）中。

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

Node.js File Upload (Express 4, MongoDB, GridFS, GridFS-Stream)

javascript

multipartform-data

mongodb

node.js

gridfs-stream