Multiple File upload in Node.js

We have covered Ajax file upload in Node.js but it was for single file at a time. In this tutorial we will learn how to do multiple file uploads using Multer and Express in Node.js.

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Our application :

I am going to develop same application as I have done in last tutorial with some additional code changes which makes it multiple file upload.

We are going to use basic FORM submit along with Ajax submit jQuery plugin to make it asynchronous. Here is our package.json file.

package.json
{
  "name": "file_upload",
  "version": "0.0.1",
  "dependencies": {
    "body-parser": "^1.14.2",
    "express": "4.13.3",
    "multer": "1.1.0"
  },
  "devDependencies": {
    "should": "~7.1.0",
    "mocha": "~2.3.3",
    "supertest": "~1.1.0"
  }
}

Run following command to install the dependencies.

npm install

Here is our Server file with multiple file upload support.

Server.js
var express =   require("express");
var bodyParser =    require("body-parser");
var multer  =   require('multer');
var app =   express();
app.use(bodyParser.json());
var storage =   multer.diskStorage({
  destination: function (req, file, callback) {
    callback(null, './uploads');
  },
  filename: function (req, file, callback) {
    callback(null, file.fieldname + '-' + Date.now());
  }
});
var upload = multer({ storage : storage }).array('userPhoto',2);

app.get('/',function(req,res){
      res.sendFile(__dirname + "/index.html");
});

app.post('/api/photo',function(req,res){
    upload(req,res,function(err) {
        //console.log(req.body);
        //console.log(req.files);
        if(err) {
            return res.end("Error uploading file.");
        }
        res.end("File is uploaded");
    });
});

app.listen(3000,function(){
    console.log("Working on port 3000");
});

The only line you need to put your focus on is this

var upload = multer({ storage : storage }).array('userPhoto',2);

Here rather than .single() we are using .array(selector,fileLimit) of Multer. Multer will accept array of files limiting to max 2 file at each time. You can of course increase the number as you may need. Rest of the code is same as previous tutorial.

Here is our HTML file.

Index.html
<html>
  <head>
    <title>File upload Node.</title>
  </head>
  <body>
      <form id="uploadForm"
          enctype="multipart/form-data"
          action="/api/photo"
          method="post">
      <input type="file" name="userPhoto" multiple />
      <input type="submit" value="Upload Image" name="submit">
      <input type='text' id='random' name='random'><br>
      <span id = "status"></span>
    </form>
  </body>
</html>

Here is our JavaScript code which we place in same HTML file. You can place it in different file. Put this code below closing tag of BODY.

index.html
  <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
  <script src="http://cdnjs.cloudflare.com/ajax/libs/jquery.form/3.51/jquery.form.min.js"></script>
  <script>
  $(document).ready(function() {
     $('#uploadForm').submit(function() {
        $("#status").empty().text("File is uploading...");
        $(this).ajaxSubmit({
            error: function(xhr) {
          status('Error: ' + xhr.status);
            },
            success: function(response) {
        console.log(response)
            $("#status").empty().text(response);
            }
    });
    return false;
    });    
});
</script>

On Form submit, we will stop the page refresh by returning FALSE and call the API using ajaxSubmit(). You can Add this code in separate file and add it below the jquery.form or copy and paste just below this line.

<script src="http://cdnjs.cloudflare.com/ajax/libs/jquery.form/3.51/jquery.form.min.js"></script>

<script>
------Paste above code ------
</script>

Running the application

To run the application, switch to project directory and type following command.

node Server.js

Running file upload app

Visit localhost:3000 to view the app. Choose multiple file from selection window and see the console.

Selecting multiple files for app

Upload done

Further enhancement

If you want to have different control for file rather than single HTML control then you need to define multiple files control in HTML with same name in order to recognize the Multer that it is array of files. Here is how you can do this. Currently we are using this.

<input type="file" name="userPhoto" multiple/>

You can write same like this.

<input type="file" name="userPhoto"/>
<input type="file" name="userPhoto"/>

There is no change in back-end code required for above change.

Conclusion

Multer is one of the easy node module you can use with Express for file upload. It allows you to add various validation and support single as well as multiple file uploads.

Shahid (UnixRoot) Shaikh

Hey there, This is Shahid, an Engineer and Blogger from Bombay. I am also an Author and i wrote a programming book on Sails.js, MVC framework for Node.js.

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30 Comments

    1. You need to write an middle ware which does the validation if its common for all routes. Other wise use login mechanism to handle session and use session to check before uploading the file.

      1. oh sorry i must’ve forgot to past it.
        part. I’m guessing you can submit extra text data with each file(like file descriptions/captions) that you can store in the database?

  1. Thank you for this simple, but useful example. I couldn’t figure out how to handle multer’s limits error until I read this. Great stuff.

  2. i tried many times to use filters but it is not working how can i use filters in multer please help me

  3. I have a problem. Instead of returning to Ajax I get white page displayed with sentence “File is uploaded”. Seems like code is not returning from server to Ajax.

  4. Great help! Do you perhaps no how to write the images names to get the names of the images as they are saved to uploads. I am wanting to use the names and save them as urls to a mongodb, so that I can retrieve the images to be added to an img tag with angular.

    1. You need to add a callback function in Multer instance.

              fileFilter : function(req, file, callback) {
                  if (["png","gif"].indexOf(file.originalname.split('.')[file.originalname.split('.').length-1]) === -1) {
                      return callback(new Error('Wrong extension type'));
                  }
                  callback(null, true);
              }
  5. sir can you help me with uploading files in mongodb using skipper-gridfs adapter
    i am getting error ” Cannot find module ‘/../build/Release/bson’ “.

  6. i am developing a project using Node.js and Angular2 , i have huge amount of objects in an array and send that using http.post() method to node server but server works on array and take more than 2 minutes and before response from server my application throws Uncaught Error : ERR_EMPTY_RESPONSE url : null , can you please suggest me solution to that.

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