Download a file from NodeJS Server using Express


Question

How can I download a file that is in my server to my machine accessing a page in a nodeJS server?

I'm using the ExpressJS and I've been trying this:

app.get('/download', function(req, res){

  var file = fs.readFileSync(__dirname + '/upload-folder/dramaticpenguin.MOV', 'binary');

  res.setHeader('Content-Length', file.length);
  res.write(file, 'binary');
  res.end();
});

But I can't get the file name and the file type ( or extension ). Can anyone help me with that?

1
266
11/10/2017 7:20:22 AM

Accepted Answer

Update

Express has a helper for this to make life easier.

app.get('/download', function(req, res){
  const file = `${__dirname}/upload-folder/dramaticpenguin.MOV`;
  res.download(file); // Set disposition and send it.
});

Old Answer

As far as your browser is concerned, the file's name is just 'download', so you need to give it more info by using another HTTP header.

res.setHeader('Content-disposition', 'attachment; filename=dramaticpenguin.MOV');

You may also want to send a mime-type such as this:

res.setHeader('Content-type', 'video/quicktime');

If you want something more in-depth, here ya go.

var path = require('path');
var mime = require('mime');
var fs = require('fs');

app.get('/download', function(req, res){

  var file = __dirname + '/upload-folder/dramaticpenguin.MOV';

  var filename = path.basename(file);
  var mimetype = mime.lookup(file);

  res.setHeader('Content-disposition', 'attachment; filename=' + filename);
  res.setHeader('Content-type', mimetype);

  var filestream = fs.createReadStream(file);
  filestream.pipe(res);
});

You can set the header value to whatever you like. In this case, I am using a mime-type library - node-mime, to check what the mime-type of the file is.

Another important thing to note here is that I have changed your code to use a readStream. This is a much better way to do things because using any method with 'Sync' in the name is frowned upon because node is meant to be asynchronous.

487
5/24/2019 5:29:47 PM

Use res.download()

It transfers the file at path as an “attachment”. For instance:

var express = require('express');
var router = express.Router();

// ...

router.get('/:id/download', function (req, res, next) {
    var filePath = "/my/file/path/..."; // Or format the path using the `id` rest param
    var fileName = "report.pdf"; // The default name the browser will use

    res.download(filePath, fileName);    
});

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