Multer fileFilter is not getting called and req.body is empty

Question

for some reason the fileFilter on multer is not getting called.

here is my Controller (i am using express routers)

const express = require('express');
const router = express.Router();
const UploadController = require('../controllers/UploadController');

router.route('/upload').post(UploadController.upload);

module.exports = router;

and this is the controller

const multer = require('multer');
const fs = require('fs');

module.exports = {
    upload: function (req, res) {
        let storage = multer.diskStorage({
            destination: function (req, file, cb) {
                console.log('here');
                const filesDir = './uploads/' + req.body.ref;
                if (!fs.existsSync(filesDir)) {
                    fs.mkdirSync(filesDir);
                }
                cb(null, filesDir);
            },
            filename: function (req, file, cb) {
                let extArray = file.mimetype.split("/");
                let extension = extArray[extArray.length - 1];
                cb(null, req.body.type + '-' + Date.now() + '.' + extension);
            },
            fileFilter : function (req, file, cb) {
                if (!file.originalname.match(/\.(jpg|jpeg|png|gif)$/)) {
                    return cb(new Error('Only image files are allowed!'), false);
                }
                cb(null, true);
            }
        })
        const upload = multer({ storage: storage }).single('file');

        upload(req, res, function (err) {
            if (err instanceof multer.MulterError) {
                res.send({
                    error: err
                });
            } else if (err) {
                res.send({
                    error: err
                });
            }else{
                res.send({
                    file: req.file,
                    body: req.body
                });
            }

        });
    }
}

I have following issues:

• The fileFilter function is not even called so its not validating files
• the req.body on the upload function (upload: function (req, res)) is empty it is only available in diskStorage and last upload function (upload(req, res, function (err)) so i cannot validate the body data also.

Answer 1

I had the same problem. the fileFilter function has to be defined inside multer, not inside the diskStorage function.

To make it a bit more readable I defined the storage and filter in variables instead of making everything inside the multer call.

// storage settings
const multerStorage = multer.diskStorage({
    destination: function(req, file, next) {
        next(null, './public/files');
    },
    filename: function(req, file, next) {
        const sanitizedName = file.originalname
            .replace('/[^a-z0-9\./gi', '-')
            .replace('/-{2,}/g', '-')
            .toLowerCase();
         const name = Date.now() + '-' + sanitizedName;

         // sending the file name to be stored in the database
         req.body.filename = name;

         next(null, name);
     },
     limits: {
         fileSize: 25000000
     }
 });

 // filter function
 const multerFilter = function(req, file, cb) {
     const ext = path.extname(file.originalname).toLowerCase();

     if (ext !== '.pdf') {
         cb(new Error('File must be in PDF format.'));
     }

     cb(null, true);
 }

And then applying the storage settings and filter function to multer:

const upload = multer({
    storage: multerStorage,
    fileFilter: multerFilter
});