how to validate a minimum number of files uploaded with multer? - node.js

Question

I want to upload files with multer, but I need that if less than 3 files are loaded simultaneously it shows an error and does not save them on my server. I know how to limit a maximum number of files, but I don't know how to limit a minimum number of files. This is my Multer configuration
const multer = require('multer');
function uploadFile() {
const storage = multer.diskStorage({
destination: './public/files',
filename: function (_req, file, cb) {
var extension = file.originalname.slice(file.originalname.lastIndexOf('.'));
cb(null, Date.now() + extension);
}
});
const upload = multer({
storage,
limits: {fileSize: 11657128, files: 3},
fileFilter: function(req, file, cb) {
let type = req.files
type?cb(null, true):cb(new Error ('no es un archivo de tipo texto plano'));
}}
).array('file');
return upload;
}
module.exports = uploadFile;

Answer 1

You can add a middleware or a validation at your routes.
app.post('/your/route', upload.array('field', 3), function (req, res) {
if (req.files.length !== 3) {
return res.status(400).json({ error: 'Three files is required'})
}
})
With array of middleware:
function validUploadLength (req, res, next) {
if (req.files.length !== 3) {
return res.status(400).json({ error: 'Three files is required'})
}
next()
}
app.post('/your/route', [upload.array('field', 3), validUploadLength], function (req, res) {
/// Your code
})