Node.js & Multer check if file is present in the request.

ensureFileIsPresent.js

module.exports = (req, res, next) => {
  if (!req.file) {
    res.status(422).json({ message: 'The file is required.' });
  } else {
    next();
  }
}

router.js

// ...
const ensureFileIsPresent = require('./middleware/ensureFileIsPresent');

router.post(upload.single('file'), ensureFileIsPresent, exampleController.doSomething);