I'm trying to connect to the DB, but the connect() function doesn't seem to work

Question

const express = require('express')
const app = express()
// const mysql = require('mysql')
const mysql = require('./db')()
const cors = require('cors')
require('dotenv').config(); 
const port = process.env.PORT || 5000

app.use(express.json())
app.use(cors())

app.listen(port, () => console.log(`${port}`))

app.get('/', (req, res) => {
  res.send("hi")
})

const connection = mysql.init()
mysql.open(connection)

This is my server.js code.

const mysql = require('mysql')
require('dotenv').config(); 

module.exports = function() {
  return {
    init: function () {
      return mysql.createConnection({
        host: process.env.HOST,
        user: process.env.USER,
        password: process.env.PASSWORD,
        database: process.env.DATABASE,
        port: process.env.PORT
      })
    },

    open: function(con) {
      con.connect(function(err) {
        // if (err) throw err
        // console.log('Connected!')
        if(err) {
          console.log('mysql connection error: '+err)
        } else {
          console.log('mysql is connected successfully.')
        }
      })
    }
  }
}

And this is my db.js code...
I expect the port number and message "mysql is connected successfully" to be printed when this code is executed. But when I run it, nothing is output except for the port number. Not even an error message.
So I can't verify that the database connection was made properly. Why is the contents of the connect() function not executed?

Answer 1

You have used same environment variable for server port and database port. Please change variable name PORT of database port to DB_PORT in .env file. Then change the environment variable name in the database port of db.js file as well.

db.js

const mysql = require("mysql");
require("dotenv").config();

module.exports = function () {
  return {
    init: function () {
      return mysql.createConnection({
        host: process.env.HOST,
        user: process.env.USER,
        password: process.env.PASSWORD,
        database: process.env.DATABASE,
        port: process.env.DB_PORT,
      });
    },

    open: function (con) {
      con.connect(function (err) {
        // if (err) throw err
        // console.log('Connected!')
        if (err) {
          console.log("mysql connection error: " + err);
        } else {
          console.log("mysql is connected successfully.");
        }
      });
    },
  };
};

example .env file

PORT=8080
HOST=localhost
USER=root
PASSWORD=root
DATABASE=dbname
DB_PORT=3306