将POST请求中的数据流存储在GridFS中，使用express、mongoDB和node.js

Question

我想找出如何直接将图像发布到GridFS，而不需要先将它作为临时文件存储在服务器上。

我正在使用Postman（Chrome扩展程序）来发布文件，我设法使用以下命令将此提交的内容存储为文件：

req.pipe(fs.createWriteStream('./test.png'));

当从服务器上的文件创建readStream时，我还可以直接将其存储到GridFS中（请参见代码）。

我有以下文件：saveFromReq.js监听POST请求，基本上只是将其传递给savePic.js。

saveFromReq.js：

var express = require('express');
var app = express();
var savePic = require('./savePic');
var fs = require('fs');
var GridStore = require('mongodb').GridStore;
var pic = './square.png';
var picID;



//When the following

 //var pic = fs.createReadStream('./square.png', {autoClose: true});

//is not commented out, and 'req' is replaced with 'pic' in the savePic function,
//the file square.png is stored correctly to GridFS

app.post('/picture', function(req, res){

    savePic(req, function(id){});
    res.writeHead(200, {'Content-Type': 'text' });
    res.end("Sucsess!\n");

});

app.listen(process.env.PORT || 3413);

保存图片.js：

var savePic = function(req, callback){


var Db = require('mongodb').Db,
    MongoClient = require('mongodb').MongoClient,
    Server = require('mongodb').Server,
    ReplSetServers = require('mongodb').ReplSetServers,
    ObjectID = require('mongodb').ObjectID,
    Binary = require('mongodb').Binary,
    GridStore = require('mongodb').GridStore,
    Grid = require('mongodb').Grid,
    Code = require('mongodb').Code,
    BSON = require('mongodb').pure().BSON,
    assert = require('assert');
    fs = require('fs');

    //When the following 

      //req.pipe(fs.createWriteStream('./test.png'));

    //is not commented out, the correct image is stored to test.png, and 
    //the sequence after req.on("data"... starts
    //(That sequence does not start at all when this is commented out..)

var fileId = new ObjectID();
var db = new Db('testDB', new Server('localhost', 27017));
// Establish connection to db
db.open(function(err, db) {


  var gridStore = new GridStore(db, 'test', 'w');

  //open 
  gridStore.open(function(err, gridStore) {
    console.log("opened");


    req.on("data", function (data) {
        console.log("data recieved");
            gridStore.write(data, function (err, gridStore) {
                if (err) {
                    console.log("error writing file");
                }
            });
        });
     req.on("end", function () {
            gridStore.close(function (err, gridStore) {
                if (!err) {
                    console.log("The file has been stored to database.");
                    db.close();
                }
            });
        });
           req.pipe(gridStore);


      });




});
callback(fileId);
};
module.exports = savePic;

任何帮助都将不胜感激！

- eirik

Answer 1

gridfs-stream让这变得非常容易：

// `gfs` is a gridfs-stream instance
app.post('/picture', function(req, res) {
  req.pipe(gfs.createWriteStream({
    filename: 'test'
  }));
  res.send("Success!");
});

- robertklep

---

谢谢，这个有效。另外，请问如何处理表单中的“文件类型多”或多个文件控件，以及如何从提交中获取原始文件名。 - hussainb

@robert，我对GridFS还不熟悉。你能告诉我在createWriteStream中的文件名是什么吗？如果我想存储字节，会发生什么情况？我需要为此创建一个新问题吗？ - JN_newbie

@Java_NewBie 文件名在这里有文档记录（http://mongodb.github.io/node-mongodb-native/api-generated/gridstore.html）。基本上，它是GridFS文档的（可选）标识符，您正在创建该文档（因此您不仅可以通过其唯一的`_id`属性访问该文档，还可以通过人类可读的字符串访问该文档）。您可以将此字符串设置为任何内容。 - robertklep

@robertklep 谢谢你，Robert。我正在尝试使用上面的代码将从设备发送的视频（字节）存储在GridFS中，但我无法存储它。我需要理解。我已经在单独的线程上发布了问题，但有人导航到此链接作为重复。谢谢。 - JN_newbie

@vinesh 你是指元数据吗？请参考 这里。 - robertklep

Answer 2

@robertklep的答案是正确的，我想在他的答案中添加一些内容。这段代码展示了如何发送存储文件的元数据。

app.post('/picture', function(req, res) {
  req.pipe(gfs.createWriteStream({
    filename: 'test'
  }).on('close', function(savedFile){
    console.log('file saved', savedFile);
    return res.json({file: savedFile});
  }));
})  

- vinesh

Answer 3

这对我在mongoose上起作用了：

 var gfs = Grid(mongoose.connection.db, mongoose.mongo);
    var writeStream = gfs.createWriteStream({
        filename: name,
        mode: 'w',
        content_type: 'video/mp4'
    });
    writeStream.on('close', function() {
        console.log('close event');
    });

    fs.createReadStream('uploads/' + name + '/' + name + '.mp4').pipe(writeStream);
    console.log('stream.write: ' + name + '/' + name + '.mp4');

我已经花了几天时间尝试让视频在客户端浏览器上播放。目前为止，我尝试了以下方法：

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

    readstream.on('data', function(data) {
        res.write(data);
        console.log(data);
    });

    readstream.on('end', function() {
        res.end();        
    });

    readstream.on('error', function (err) {
        console.log('An error occurred!', err);
        throw err;
    });

我的MongoDB数据如下：

db.fs.chunks.find() { "_id" : ObjectId("5757e76df14741bf0391aaca"), "files_id" : ObjectId("5757e76df14741bf0391aac8"), "n" : 0, "data" : BinData(0,"AAAAIGZ0eXBpc29....

并且contentType为'video/mp4':

浏览器端的日志打印如下：

Object { 0: "�", 1: "�", 2: "�", 3: " ", 4: "f", 5: "t", 6: "y", 7: "p", 8: "i", 9: "s", 85003 more… }

请问有谁可以救我一命吗？希望你不要认为我的帖子在这里不方便。

- udito

Answer 4

完整的代码，使用Node.js中的GridFS将txt文件插入MongoDB。这个很好用。

var mongoose=require("mongoose");
var gridfsstream=require("gridfs-stream");
var fs=require("fs");
mongoose.connect("mongodb://localhost:27017/testimage");
var conn=mongoose.connection;
gridfsstream.mongo=mongoose.mongo;
conn.once("open",function()
{
    console.log("database connected successfully");
    var gfs=gridfsstream(conn.db);
    var writestream=gfs.createWriteStream({
        filename:"danger.txt"
    });
    fs.createReadStream("sivakasi.txt").pipe(writestream);
    writestream.on("close",function(file)
    {
        console.log(file.filename +"stored successfully into mongodb using gridfs");
    });
    writestream.on("error",function(file)
    {
        console.log(file.filename +"not stored into mongodb using gridfs");
    });
});
conn.on("error",function()
{
    console.log("database not connected try again!!!");
});

`

- vigneshRavi

Answer 5

完整的代码来将html中的图像上传到nodejs存储在mongodb中，使用gridfs系统，并在服务器上显示该图像。这段代码运行良好。

var express=require("express");
var bodyparser=require("body-parser");
var multer=require("multer");
var app=express();
var upload = multer({ dest: '/tmp/'});
app.use(bodyparser.urlencoded({extended:false}));
app.post("/uploadimage",upload.single("file"),function(request,response)
{
    var mongoose=require("mongoose");
    var gridfsstream=require("gridfs-stream");
    var fs=require("fs");
    mongoose.connect("mongodb://localhost:27017/testimage");
    var con=mongoose.connection;
    gridfsstream.mongo=mongoose.mongo;
    con.once("open",function()
    {
        console.log("test image database connected successfully");
        var gfs=gridfsstream(con.db);
        var readstream=fs.createReadStream(request.file.originalname);
        var writestream=gfs.createWriteStream({
            filename:"mentorpicthree.jpg"
        });
        readstream.pipe(writestream);
        writestream.on("close",function()
        {
            console.log("image stored in mongodb database successfully");
            fs.readFile(request.file.originalname,function(err,data)
            {
                if(err)
                {
                    response.writeHead(404,{"Content-Type":"text/plain"});
                    console.log("error");

                }
                else
                {
                        response.writeHead(200,{"Content-Type":"image/jpg"});
                        response.end(data);
                }
            });
        });
        writestream.on("error",function()
        {
            console.log("image not stored in mongodb database");
        });

    });
    con.on("error",function()
    {
        console.log("database not connected try again!!!");
    });

});
app.listen(8086,function()
{
    console.log("server running on port 8086");
});

<html>
<head>
    <title>FILE UPLOAD</title>
</head>
<body>
<p>Ryan Dhal</p>
<form action="http://127.0.0.1:8086/uploadimage" method="POST" enctype="multipart/form-data">
    <input type="file" name="file">
    <br>
    <input type="submit" value="UPLOAD">
</form>
</body>
</html>

- vigneshRavi