Cannot app.use(multer). "requires middleware function" error

Question

I'm just starting learning NodeJS and I am stuck with a problem. I would like to upload files to my server. To do so I searched and found out this module multer. Doing as the example on GitHub works:

var express = require('express');
var multer = require('multer');
var upload = multer({ dest: 'uploads/' });

var app = express()

app.post('/uploadImage', upload.single('image'), function(req, res) {
    console.log(req.file);
});

On posting an image with FormData to /uploadImage the image is saved in the uploads/ directory. The thing is the image is saved with a strange name and I would like to save it with its original name. To do so I understood that I would have to call app.use(multer({ dest: 'uploads/' }))' and then I would be able to access req.file in my function like:

app.post('/uploadImage', function(req, res) {
    console.log(req.file);
});

But I get an error on trying app.use():

TypeError: app.use() requires middleware functions
    at EventEmitter.use (project\node_modules\express\lib\application
.js:209:11)

Im using NodeJS 0.12.7 and Express 4.13.1

How can I achieve that upload? Thanks.

Oh my... I swer I have searched here... Thanks stdob... But well, strangely (for me) it stills uploads the file automatically that way... I though I would be able to control and write it with fs... Ill find a way, thx — João Menighin
– João Menighin, Commented Jul 18, 2015 at 22:28

daparic · Accepted Answer · 2015-12-01 04:05:01Z

62

You need to use app.use(multer({dest:'./uploads/'})) in the form of one of these:

app.use(multer({dest:'./uploads/'}).single(...));
app.use(multer({dest:'./uploads/'}).array(...));
app.use(multer({dest:'./uploads/'}).fields(...));

ie:

app.use(multer({dest:'./uploads/'}).single('photo'));

And be sure to have something like:

<form action="/postPhotos" enctype="multipart/form-data" method="post">
    <input type="file" name="photo">
    <input type="submit" value="Upload photo">
</form>

In your html.

edited Dec 1, 2015 at 4:05

daparic

4,6222 gold badges47 silver badges46 bronze badges

answered Jul 27, 2015 at 23:28

Ruben Marrero

1,3921 gold badge10 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

baldr · Accepted Answer · 2016-03-15 20:17:24Z

23

var app = require('express');

var multer = require('multer');

app=express();

app.use(multer({dest:__dirname+'/file/uploads/'}).any());

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

    console.log(req.files);

    res.redirect('/');

});

edited Mar 15, 2016 at 20:17

baldr

2,99911 gold badges46 silver badges63 bronze badges

answered Mar 15, 2016 at 19:46

Homar Roman Franco

2412 silver badges2 bronze badges

2 Comments

William Price Over a year ago

This answer would be improved if it contained some explanation of how it answers the question and solves the problem.

William Price Over a year ago

StackOverflow requests that you post questions, comments, and answers in English only, please. (En inglés, por favor.) Also, use the edit link to update your answer directly.

Salvatorelab · Accepted Answer · 2016-05-13 06:59:24Z

12

The answer from @127.0.0.1 is correct, but in case you are using Express Router, the code changes a little bit:

var express = require('express');
var multer = require('multer');

var router = express.Router();

var uploads = multer({
  dest: 'public/uploads/'
});

router.post('/upload', uploads.single('avatar'), function(req, res, next) {
  console.log(req.file);

  //...
});

And the important bit, the form encoding should be enctype="multipart/form-data" as already said, like that:

<form action="/upload" enctype="multipart/form-data" method="post">
    <input type="file" name="avatar">
    <input type="submit" value="Go avatar go!">
</form>

answered May 13, 2016 at 6:59

Salvatorelab

11.9k7 gold badges55 silver badges81 bronze badges

4 Comments

Hanzo Over a year ago

Hi, I'm using multer, expres, ng2-file-upload stack and with your exactly code doesn't works for me. The req.file is undefined and the info of my file is on req.files(on my html I dont have the multiple selector). When I click to upload on my button the server return file uploaded bt the file is not present on server. What would be doing wrong?

Salvatorelab Over a year ago

I would suggest testing it without angular first. I mean sending the request to the backend directly with Postman or CURL or your favorite tool. If that works, the problem is the frontend. If it doesn't, the problem is the backend. It is not going to solve the problem, but it will help you solve it faster.

Hanzo Over a year ago

If I add this app.use(multer({storage:storage}).single('file')); works fine but not as expected with callbacks. Could you check this question? stackoverflow.com/questions/44165037/…

Paul W Over a year ago

Salvatorelab, I've been searching for 2 hrs+ trying to figure out why the I couldn't debug upload.single is not a function while use express router. Just want to point that out since that's not what the OP was trying to solve, might help someone else.

Aditya · Accepted Answer · 2017-05-22 11:42:50Z

You can't change the file name using multer but you can use Node.js stream and fs module to copy the content of already uploaded file to new file(set as original file name) on same folder and delete old one.

First of all import fs, path and multer in your node script.

var express = require('express');
var multer = require('multer');
var fs = require('fs');
var pathModule = require('path');

Now, set destination directory of any type of files using multer as below.

var app = express();
app.use(multer({dest:__dirname+'/resoucres/'}).any());

Now use stream and fs to resolve your issue.

app.post('/uploadImage', function(request, response) {
    var readerStream = fs.createReadStream(request.files[0].path);
    var dest_file = pathModule.join(request.files[0].destination, request.files[0].originalname);
    var writerStream = fs.createWriteStream(dest_file);

    var stream = readerStream.pipe(writerStream);
    stream.on('finish', function(){
        fs.unlink(request.files[0].path);
    });
});

josliber · Accepted Answer · 2015-09-12 12:12:33Z

6

Since version 1.0.0

var upload = multer({ dest: 'tmp/' });
app.post('/file_upload', upload.single('photo'), function (req, res) {

edited Sep 12, 2015 at 12:12

josliber

44.4k12 gold badges104 silver badges136 bronze badges

answered Sep 12, 2015 at 10:43

Jacek Wojcik

1,2734 gold badges20 silver badges34 bronze badges

1 Comment

Ashh Over a year ago

what is upload.single('photo') here??

Lekan Stephen · Accepted Answer · 2016-05-20 10:51:01Z

4

Changing to app.use(multer({dest:'./uploads/'}).single('photo')); in the app.js works for me to start the server

answered May 20, 2016 at 10:51

Lekan Stephen

1112 bronze badges

1 Comment

Dieter Meemken Over a year ago

Can you explain a bit more?

Community · Accepted Answer · 2017-05-23 12:18:25Z

2

I encountered the same problem. And I solved it. For the first problem, how to get the original file name? I printed the whole request and found we could get original name by using the path "req.file.originalname"

and the other question, how to use "app.use()"?
refers: here

edited May 23, 2017 at 12:18

CommunityBot

11 silver badge

answered Jul 5, 2016 at 7:22

Haifeng Fu

233 bronze badges

Collectives™ on Stack Overflow

Cannot app.use(multer). "requires middleware function" error

7 Answers 7

Comments

2 Comments

4 Comments

Comments

1 Comment

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

Comments

2 Comments

4 Comments

Comments

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related