How to write a function like middleware but can have some parameters - node.js

Question

I want to modify the function (checkAuth) to check if a User have a specific Permissions. If yes => continue, else will print the error. But it return 'undefinded'.
I want to pass two parameters (userId and Permission_CODE). I get userId from parsing token.
I used middleware but it seemed not allow to pass other parameters (except req, res, next)
This is for Windows server, running NodeJS and Express
checkToken.js
const jwt = require('jsonwebtoken');
module.exports = (req, res, next) => {
try {
const token = req.headers.authorization.split(" ")[1];
const decoded = jwt.verify(token, 'secretKey')
req.decoded = decoded
next();
}
catch(error){
return res.status(401).json({
message: "Auth failed"
})
}
}
checkAuth.js
const User = require('../models/user')
module.exports = (userId, action_code) => {
User
.findOne({ _id: userId })
.populate({
path: 'user_role',
populate: {
path: 'permissions',
match: { action_code: action_code }
}
})
.exec((err, user) => {
if (err) {
return console.log(err)
}
else if (user.user_role.permissions.length == 0) {
return false
}
else {
console.log(user.user_role.permissions)
return true
}
})
}
}
Using in API
router.get('/luu',checkToken,(req, res) => {
console.log(checkAuth(req.decoded.userId, "1")) //It returned undefinded
})
This is the code of program: https://github.com/phongluudn1997/express-testing.git

Answer 1

In checkAuth.js, your module is asynchronous, according to this you can't just return true/false, you've to return result in a callback.
module.exports = (userId, action_code, cb) => {
User
.findOne({ _id: userId })
.populate({
path: 'user_role',
populate: {
path: 'permissions',
match: { action_code: action_code }
}
})
.exec((err, user) => {
if (err) {
return cb(err, false)
}
else if (user.user_role.permissions.length == 0) {
return cb(null, false);
}
else {
console.log(user.user_role.permissions)
return cb(null, true);
}
})
}
}
And you must call your module like this:
router.get('/luu',checkToken,(req, res) => {
checkAuth(req.decoded.userId, "1", function(err, result){
if(err) console.log(err);
else if(!result) console.log("False");
else console.log("True");
});
})

Answer 2

You're trying to return from callback which does not work. You could use async/await like:
module.exports = async (userId, action_code) => {
let permission;
try {
const user = await User
.findOne({ _id: userId })
.populate({
path: 'user_role',
populate: {
path: 'permissions',
match: { action_code: action_code }
}
})
if (user.user_role.permissions.length == 0) {
permission = false
} else {
console.log(user.user_role.permissions)
permission = true
}
} catch (e) {
throw e
}
return permission
}
Make your route async function as well:
router.get('/luu',checkToken, async (req, res) => {
try {
console.log(await checkAuth(req.decoded.userId, "1"))
} catch (e) {
console.error(e)
}
})
or make this into another middleware function like:
// checkPermission.js
module.exports = (req, res, next) => {
User
.findOne({ _id: userId })
.populate({
path: 'user_role',
populate: {
path: 'permissions',
match: { action_code: action_code }
}
})
.exec((err, user) => {
if (err) {
return next(err)
}
else if (user.user_role.permissions.length == 0) {
req.permissions = false
}
else {
console.log(user.user_role.permissions)
req.permissions = true
}
})
next();
}
Then in your route:
const checkPermission = require('./checkPermission.js')
router.get('/luu',checkToken, checkPermission, (req, res) => {
console.log(req.permissions)
})