Uploading multiple files with multer, but from different fields?

Question

How can I have multer accept files from multiple file type fields?

I have the following code that uploads a single file, using multer in node.js:

var storage =   multer.diskStorage({
  destination: function (req, file, callback) {
    callback(null, './public/uploads');
  },
  filename: function (req, file, callback) {
    callback(null, file.fieldname + '-' + Date.now());
  }
});

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

app.post('/rest/upload', upload.array('video', 1), function(req, res, next){
    ...
}

From the following form, on the condition only the video field has a value (if I specify both I get an 'Unexpected field' error):

<form action="/rest/upload" method="post" enctype="multipart/form-data">
   <label>Video file: </label> <input type="file" name="video"/> 
   <label>Subtitles file: </label> <input type="file" name="subtitles"/> 
   <input type="submit"/>
</form>

It is not clear from the documentation how to approach this? Any suggestions would be appreciated. BTW I have tried the following parameter variations, without success:

app.post('/rest/upload', [upload.array('video', 1), upload.array('subtitles', 1)] ...
app.post('/rest/upload', upload.array('video', 1), upload.array('subtitles', 1), ...
app.post('/rest/upload', upload.array(['video', 'subtitles'], 1),  ...

Answer 1

What you want is upload.fields():

app.post('/rest/upload',
         upload.fields([{
           name: 'video', maxCount: 1
         }, {
           name: 'subtitles', maxCount: 1
         }]), function(req, res, next){
  // ...
}

Answer 2

Did you try to use multer().any()?

Answer 3

Using Multer Upload Files From Two Fields of Separate Forms on Different Pages In this example I have two fields - resume and image. Resume in one form and Image in other. Both are on separate pages. First import dependencies

const path = require('path'); // for getting file extension
const multer = require('multer'); // for uploading files
const uuidv4 = require('uuidv4'); // for naming files with random characters

Define fileStorage and fileFilter const fileStorage = multer.diskStorage({ destination: (req, file, cb) => { // setting destination of where the file to be stored

    if (file.fieldname === "resume") { // if uploading resume
      cb(null, 'resumes');
    } else { // else uploading image
      cb(null, 'images');
    }
  },
  filename: (req, file, cb) => { // naming file
    cb(null, file.fieldname+"-"+uuidv4()+path.extname(file.originalname));
  }
});

const fileFilter = (req, file, cb) => {
  if (file.fieldname === "resume") { // if uploading resume
    if (
      file.mimetype === 'application/pdf' ||
      file.mimetype === 'application/msword' ||
      file.mimetype === 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
    ) { // check file type to be pdf, doc, or docx
      cb(null, true);
    } else {
      cb(null, false); // else fails
    }
  } else { // else uploading image
    if (
      file.mimetype === 'image/png' ||
      file.mimetype === 'image/jpg' ||
      file.mimetype === 'image/jpeg'
    ) { // check file type to be png, jpeg, or jpg
      cb(null, true);
    } else {
      cb(null, false); // else fails
    }
  }
};

Middleware for multer

app.use(
  multer(
    { 
      storage: fileStorage, 
      limits:
        { 
          fileSize:'2mb' 
        }, 
      fileFilter: fileFilter 
    }
  ).fields(
    [
      { 
        name: 'resume', 
        maxCount: 1 
      }, 
      { 
        name: 'image', 
        maxCount: 1 
      }
    ]
  )
);

And then call your routes. You may need to add csrf protection or authentication along with this for security. But this should work fine.