28

我是 Node.js 的新手。谁能给我一个例子，说明如何使用 GridFS 存储和检索二进制数据，例如图像，使用 Node.js 和 Mongoose？我需要直接访问 GridFS 吗？

4

4 回答 4

27

我对这里评分最高的答案不满意，所以我提供了一个新答案：我最终使用了 可以通过 npm 安装的节点模块“gridfs-stream” （那里有很棒的文档！）。有了它，再加上猫鼬，它可能看起来像这样：

var fs = require('fs');
var mongoose = require("mongoose");
var Grid = require('gridfs-stream');
var GridFS = Grid(mongoose.connection.db, mongoose.mongo);

function putFile(path, name, callback) {
    var writestream = GridFS.createWriteStream({
        filename: name
    });
    writestream.on('close', function (file) {
      callback(null, file);
    });
    fs.createReadStream(path).pipe(writestream);
}

请注意，路径是本地系统上文件的路径。

至于我的文件读取功能，就我而言，我只需要将文件流式传输到浏览器（使用 express）：

try {
    var readstream = GridFS.createReadStream({_id: id});
    readstream.pipe(res);
} catch (err) {
    log.error(err);
    return next(errors.create(404, "File not found."));
}
于 2014-04-09T16:34:37.253 回答
24

到目前为止的答案都很好，但是，我相信在这里记录如何使用官方的mongodb nodejs 驱动程序而不是依赖于诸如“gridfs-stream”之类的进一步抽象将是有益的。

之前的一个答案确实使用了官方的 mongodb 驱动程序，但是他们使用了 Gridstore API；此后已被弃用，请参见此处。我的示例将使用新的GridFSBucket API。

这个问题非常广泛，因此我的答案将是整个 nodejs 程序。这将包括设置 express 服务器、mongodb 驱动程序、定义路由以及处理 GET 和 POST 路由。

使用的 Npm 包

  • express（nodejs Web 应用程序框架，用于简化此代码段）
  • multer（用于处理多部分/表单数据请求）
  • mongodb（官方 mongodb nodejs 驱动）

GET photo 路由以 Mongo ObjectID 作为参数来检索图像。

我配置 multer 将上传的文件保存在内存中。这意味着照片文件不会随时写入文件系统，而是直接从内存流式传输到 GridFS。

/**
 * NPM Module dependencies.
 */
const express = require('express');
const photoRoute = express.Router();

const multer = require('multer');
var storage = multer.memoryStorage()
var upload = multer({ storage: storage, limits: { fields: 1, fileSize: 6000000, files: 1, parts: 2 }});

const mongodb = require('mongodb');
const MongoClient = require('mongodb').MongoClient;
const ObjectID = require('mongodb').ObjectID;
let db;

/**
 * NodeJS Module dependencies.
 */
const { Readable } = require('stream');

/**
 * Create Express server && Routes configuration.
 */
const app = express();
app.use('/photos', photoRoute);

/**
 * Connect Mongo Driver to MongoDB.
 */
MongoClient.connect('mongodb://localhost/photoDB', (err, database) => {
  if (err) {
    console.log('MongoDB Connection Error. Please make sure that MongoDB is running.');
    process.exit(1);
  }
  db = database;
});

/**
 * GET photo by ID Route
 */
photoRoute.get('/:photoID', (req, res) => {
  try {
    var photoID = new ObjectID(req.params.photoID);
  } catch(err) {
    return res.status(400).json({ message: "Invalid PhotoID in URL parameter. Must be a single String of 12 bytes or a string of 24 hex characters" }); 
  }

  let bucket = new mongodb.GridFSBucket(db, {
    bucketName: 'photos'
  });

  let downloadStream = bucket.openDownloadStream(photoID);

  downloadStream.on('data', (chunk) => {
    res.write(chunk);
  });

  downloadStream.on('error', () => {
    res.sendStatus(404);
  });

  downloadStream.on('end', () => {
    res.end();
  });
});

/**
 * POST photo Route
 */
photoRoute.post('/', (req, res) => {
  upload.single('photo')(req, res, (err) => {
    if (err) {
      return res.status(400).json({ message: "Upload Request Validation Failed" });
    } else if(!req.body.name) {
      return res.status(400).json({ message: "No photo name in request body" });
    }
    
    let photoName = req.body.name;
    
    // Covert buffer to Readable Stream
    const readablePhotoStream = new Readable();
    readablePhotoStream.push(req.file.buffer);
    readablePhotoStream.push(null);

    let bucket = new mongodb.GridFSBucket(db, {
      bucketName: 'photos'
    });

    let uploadStream = bucket.openUploadStream(photoName);
    let id = uploadStream.id;
    readablePhotoStream.pipe(uploadStream);

    uploadStream.on('error', () => {
      return res.status(500).json({ message: "Error uploading file" });
    });

    uploadStream.on('finish', () => {
      return res.status(201).json({ message: "File uploaded successfully, stored under Mongo ObjectID: " + id });
    });
  });
});

app.listen(3005, () => {
  console.log("App listening on port 3005!");
});

我写了一篇关于这个主题的博客文章；是对我的回答的详细说明。在这里可用

进一步阅读/灵感：

于 2017-11-08T22:27:04.750 回答
9

我建议看看这个问题：MongoDB GridFS Saving Files with Node.JS 的问题

从答案中复制的示例（归功于 christkv）：

// You can use an object id as well as filename now
var gs = new mongodb.GridStore(this.db, filename, "w", {
  "chunk_size": 1024*4,
  metadata: {
    hashpath:gridfs_name,
    hash:hash,
    name: name
  }
});

gs.open(function(err,store) {
  // Write data and automatically close on finished write
  gs.writeBuffer(data, true, function(err,chunk) {
    // Each file has an md5 in the file structure
    cb(err,hash,chunk);
  });
});
于 2011-11-15T12:29:43.810 回答
3

看起来 writeBuffer 已经被弃用了。

/Users/kmandrup/private/repos/node-mongodb-native/HISTORY:
   82  * Fixed dereference method on Db class to correctly dereference Db reference objects. 
   83  * Moved connect object onto Db class(Db.connect) as well as keeping backward compatibility.
   84: * Removed writeBuffer method from gridstore, write handles switching automatically now.
   85  * Changed readBuffer to read on Gridstore, Gridstore now only supports Binary Buffers no Strings anymore.
于 2012-04-09T20:53:41.617 回答