Where should i put createPool({ ... }) in mysql/mysql2? - mysql

Question

I am developing an e-commerce website and as of now I have these basic backend codes:
const port = process.env.PORT || 5429
const express = require ('express')
const server = express ()
const cors = require('cors')
server.use (cors ())
const bodyParser = require('body-parser')
server.use (bodyParser.json ())
server.use (bodyParser.urlencoded ({ extended: true }))
server.listen (port, () => {
console.log (`Server port listening to: ${ port }`)
})
Now I am having trouble where to put the
const mysql = require ('mysql') together with mysql.createPool ({ ... }).
Should i put them here before the server.listen? or
Should I go with this?
module.exports = class Database {
connectWithPool () {}
}
and put is under here:
const Database = require ('./db.js')
const db = new Database ()
module.exports = class User {
login (req, res) {
....
db.connectWithPool ()
....
}
}
and attach the user.login in route
const User = require ('user.js')
const user = new User ()
module.exports = class Routes {
constructor (server) {
this.server = server
}
routeUser () {
this.server.post ('/api/user', user.login)
}
}
Your suggestions. Because its not very clear to me how createConnection and createPool works internally.
P.S: disregard if there's an error to my codes. I just want to explain my own idea.