MongoDb BSON:File Upload & Download in express.js using mongoose & multer

We know that a file as binary data can be saved in different DBMS system like

MySQL,MSSQL,Oracle. Today we will explore how a file can be uploaded in mongodb.

Their are two ways one is BSON data type in which size need to be less than 16

kb.

BSON is a binary serialization format used to store documents and make remote

procedure calls in MongoDB

Lets first create a express application using express generator.

express --view=ejs express-mongoose-bson

Now install required dependencies

By package.json look like

{

"name": "express-mongoose-bson",

"version": "0.0.0",

"private": true,

"scripts": {

"start": "node ./bin/www"

},

"dependencies": {

"cookie-parser": "~1.4.4",

"debug": "~2.6.9",

"dotenv": "^16.4.5",

"ejs": "~2.6.1",

"express": "~4.16.1",

"http-errors": "~1.6.3",

"mongoose": "^8.3.3",

"morgan": "~1.9.1",

"multer": "^1.4.5-lts.1"

}

}

Here we are installing multer,dotenv,mongoose packages.

Run npm i.

create .env file in root folder with content

MONGO_URI = mongodb://sangram:sangram%2381@127.0.0.1:27017

/phenixDb?directConnection=true&serverSelectionTimeoutMS=2000&

authSource=admin&appName=mongosh+2.2.3

Now add upload.js in root folder.

content of upload.js'

var multer = require("multer");

var storage = multer.diskStorage({

destination: (req, file, cb) => {

cb(null, './public/uploads/profile_pic/')

},

filename: function (req, file, cb) {

var fileparts = file.originalname.split(".");

var ext = fileparts[fileparts.length - 1];

cb(null, file.fieldname + "-" + Date.now() + "." + ext);

}

});

var upload = multer({ storage: storage });

module.exports = upload;

also add connection.js in root folder with following content.

var mongoose = require("mongoose");

mongoose.connect(process.env.MONGO_URI,{ });

module.exports = mongoose;

create models folder in root location & add image.js in it.

Here is content of image.js

var mongoose = require("mongoose");

var connection = require("../connection");

var imageSchema = new mongoose.Schema({

name: String,

desc: String,

filename: String,

img: {

data: Buffer,

contentType: String,

},

});

var imageModel = new mongoose.model("Image", imageSchema);

module.exports = {

ImageModel: imageModel,

ImageSchema: imageSchema,

};

Now add uploads folder in public folder & inside uploads folder

add profile_pic folder.

Now create demo.js inside rotes folder with follwoing content.

var express = require("express");

var router = express.Router();

var { ImageModel } = require("../models/image");

var upload = require("../upload");

var fs = require("fs");

var path = require("path");

var mongoose = require("mongoose");

router.post("/", upload.single("image"), async (req, res, next) => {

var obj = {

name: req.body.name,

desc: req.body.desc,

filename: req.file.filename,

img: {

data: fs.readFileSync(

path.join("./public/uploads/profile_pic/" + req.file.filename)

),

contentType: "image/png",

},

};

try {

var item = await ImageModel.create(obj);

res.json({ item: item });

} catch (exp) {

console.log(exp.message.toString());

res.status(500).send({ msg: "An error occurred", error: exp });

}

});

//get image --var mongoose = require("mongoose");

router.get("/:fileId", async (req, res) => {

try {

var result = await ImageModel.find(

{ _id: new mongoose.Types.ObjectId(req.params.fileId) },

{}

);

var fileName = result[0].filename;

var mimeType = result[0].img.contentType;

var buffer = result[0].img.data;

res.contentType(mimeType);

res.send(buffer);

} catch (err) {

res

.status(500)

.send({ msg: "An error occurred", error: err.message.toString() });

}

});

module.exports = router;

Inside app.js add

var demoRouter = require('./routes/demo');

and

app.use('/demo', demoRouter);

in suitable location.

Now we are ready to run our application.Usually testing can be done using

postman.

For uploading image

Here is curl for that

curl --location 'localhost:3000/demo' \

--form 'name="sangram"' \

--form 'desc="sangram desai"' \

--form 'image=@"/home/sangram/Pictures/Photo.jpg"'

Output:

{

"item": {

"name": "sangram",

"desc": "sangram desai",

"filename": "image-1714460945726.jpg",

"img": {

"data": {

"type": "Buffer",

"data": [some data here truncated]

}

},

"_id": "6630991140528fe1e6bfa8d4",

"__v": 0

}

}

Downloading File:

curl --location 'http://localhost:3000/demo/6630991140528fe1e6bfa8d4'

Here we are passing it of record created in previous curl call.

The complete code of this application can be found at

https://github.com/gitsangramdesai/express-mongoose-bson.