Connect to database from server.js file on Angular and NodeJS app - node.js

Question

I have two files in my angular project: server.js and db_connection.js. I'm hosting the project on Heroku.
The server.js currently runs because, in my package.json, I have "start": "node server.js"
I want to connect to the database as well, but I want to put that in a separate file called db_connection.js. How should I go about making sure the code in that file runs? Do I call it from server.js? If so, how so?
My files:
server.js:
const express = require('express');
const app = express();
const path = require('path');
app.use(express.static(__dirname + '/dist/my-app'));
app.listen(process.env.PORT || 8080);
// PathLocationStrategy
app.get('*', function (req, res) {
res.sendFile('dist/my-app/index.html' , { root : __dirname});
});
console.log('Console Listening')
db_connection.js:
var mysql = require('mysql');
var con = mysql.createConnection({
host: "my_server.net",
user: "my_username",
password: "my_password"
});
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
});

Answer 1

You could do something like this.
server.js
const express = require('express');
const app = express();
const path = require('path');
const db = require('./db_connection')
app.use(express.static(__dirname + '/dist/my-app'));
app.listen(process.env.PORT || 8080);
// PathLocationStrategy
app.get('*', function (req, res) {
res.sendFile('dist/my-app/index.html' , { root : __dirname});
});
app.get('/getSomethingFromDB', db.getSomethingFromDB)
app.post('/postSomethingToDB', db.postSomethingToDB)
console.log('Console Listening')
db_connection.js
const mysql = require('mysql')
const con = mysql.createConnection({
host: "my_server.net",
user: "my_username",
password: "my_password",
database: 'my_db_name'
});
con.connect( err => {
if (err) throw err;
console.log("Connected")
});
module.exports = {
getSomethingFromDB: (req, res) => {
const getQuery = `SELECT * FROM some_table WHERE condition`
con.query(getQuery, (error, results, fields) => {
if (error) {
return res.status(500).send("DB Error")
} else {
return res.status(200).send(results)
}
})
},
postSomethingToDB: (req , res) => {
// Your code for post requests
},
// Similarly other functions
}