Return middleware from middleware - node.js

Question

I am using express-validator and would like to have different checks based on a value in the request body.
I have created a function for this, but I am not getting any responses back (i.e. express just hangs.):
validation/profile.js
module.exports = function (req,res,next) {
if (req.body.type == 'teacher') {
return check('name').exists().withMessage('Name is required'),
} else {
return check('student_id').exists().withMessage('Student id is required'),
}
}
app.js
router.put('/', require('./validation/profile'), (req, res, next) => {
const errors = validationResult(req).formatWith(errorFormatter)
if (!errors.isEmpty()) {
return res.status(422).json({ errors: errors.mapped() })
} else {
res.send(req.user)
}
})
If however, I write my function as a normal function (not as middleware with 3 params) and call it, it all works. But this way, I won't have access to the request object. I have to "hard-code" the params.
validation/profile.js
module.exports = function (type) {
if (type == 'teacher') {
return check('name').exists().withMessage('Name is required'),
} else {
return check('student_id').exists().withMessage('Student id is required'),
}
}
app.js
router.put('/', require('./validation/profile')('teacher'), (req, res, next) => {
const errors = validationResult(req).formatWith(errorFormatter)
if (!errors.isEmpty()) {
return res.status(422).json({ errors: errors.mapped() })
} else {
res.send(req.user)
}
})
Any suggestions on how could I achieve having different checks based on a value in the request body?

Answer 1

The express-validator check API creates the middleware, you should attach it to express directly or call it yourself as express would.
// Use routers so multiple checks can be attached to them.
const teacherChecks = express.Router();
teacherChecks.use(check('name').exists().withMessage('Name is required'));
const studentChecks = express.Router();
studentChecks .use(check('student_id').exists().withMessage('Student id is required'));
module.exports = function (req,res,next) {
if (req.body.type == 'teacher') {
teacherChecks(req, res, next);
} else {
studentChecks(req, res, next);
}
}
You could also potentially use oneOf to do the same thing.
router.put('/', oneOf([
check('name').exists().withMessage('Name is required'),
check('student_id').exists().withMessage('Student id is required')
], 'Invalid request body'), (req, res, next) => {
const errors = validationResult(req).formatWith(errorFormatter)
if (
!errors.isEmpty()
) {
return res.status(422).json({errors: errors.mapped()})
}
else {
res.send(req.user)
}
});