I've been trying to use JSON configuration file to route node application. I tried to search many ways to do this...but could not success yet.

(The reason that I want to do is, the structure of my project divided as module, and each module folder have its own route code.)

/config/module.json

: Define module structure, and the path that route files are stored in.

[
    {
        "name" : "my-auth",
        "route" : "my-auth/api",
        "description" : "Some description about module"
    },
    {
    }
...]

/index.js

const routeEngine = require('./router/engine')

// Use ./router/engine/index.js to route '/api/v1'
app.use('/api/v1', routeEngine)

...

/router/engine/index.js

const fs = require('fs')
const config = require('../../config/module.json')
const express = require('express')
const app = express()
const path = require('path')

module.exports = (app) => {
        
    for (const value of config) {

        const poo = fs.readdirSync(path.join(__dirname, '../../module/', value.route))
        
        poo.forEach(file => {

            const name = file.substr(0, file.indexOf('.'))
            
            require(path.join(__dirname, '../../module/', value.route, '/', name))(app)
            
        })
    }
}

/module/my-auth/api/auth.js

: Many modules include my-auth is in module folder. One module can have several router files.

const express = require('express')
const router = express.Router()

router.get('/product/all', async (req, res) => { some code }

module.exports = router

This is the errors that I got.

(node:18374) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'apply' of undefined
    at /home/node_modules/express/lib/router/index.js:635:15
    at next (/home/node_modules/express/lib/router/index.js:260:14)
    at Function.handle (/home/node_modules/express/lib/router/index.js:174:3)
    at router (/home/node_modules/express/lib/router/index.js:47:12)
    at poo.forEach (/home/router/engine/index.js:26:83)
    at Array.forEach (<anonymous>)
    at module.exports (/home/router/engine/index.js:16:13)
    at Layer.handle [as handle_request] (/home/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/home/node_modules/express/lib/router/index.js:317:13)
    at /home/node_modules/express/lib/router/index.js:284:7
(node:18374) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 2)