Node unhandel promises and imports oop - mysql

Question

My code have an obj name SQLFeeter that need to do the sql interaction which get the data post it and pass it along I have some problem which is one imports. The babel doesn't work second while I try to get the data and pass it
const express = require('express');
const router = express.Router();
const mysql = require('mysql')
/*
--------------------------------------
This will handel all get requests
--------------------------------------
*/
/*
//sqlInteractuin test
const SqlDataGetter = require('../../sqlInteraction/GetData');
//import SqlDataGetter from "./sqlInteraction/GetData";
let SqlGetter = new SqlDataGetter
*/
class SqlDataGetter {
constructor()
{
this.con = mysql.createConnection({
host: "localhost",
user: "XXX",
password: "XXX",
database: "APP"
});
}
GetClients()
{
let con = mysql.createConnection({
host: "localhost",
user: "XXX",
password: "AAA",
database: "APP"
});
let resultFromSql = null;
con.connect(function(err) {
if (err) throw err;
let sql_query = "SELECT * FROM contacts"
con.query(sql_query , function (err, result, fields) {
if (err) throw err;
//console.log(fields);
console.log(result);
resultFromSql = result;
});
return resultFromSql;
});
}
Tester()
{
//return this.con
//console.log(this.con)
return 'hello world'
}
}
router.get('/' , async (req , res) =>
{
//Need to make an obj that take the data and do all the querys
res.status(200).send("DataBack");
});
router.get('/Clients' , async (req , res) =>
{
let sql_getter = new SqlDataGetter();
const Clients = sql_getter.GetClients();
console.log(Clients);
SqlDataGetter.GetClients()
res.status(200);
res.send({ respond : Clients});
});
While I am trying to run this at first it works on stand alone but when I create the ajax request it saying GetClients is not a function. And when I try to make the connection to be a property of this object as this.con when I activate this.con.query undifend property query of undifend.

Answer 1

If you use promise-mysql instead of mysql then you'll get promises from the method calls, which will make it easier to work with:
const mysql = require('promise-mysql');
Then your class would look like this:
class SqlDataGetter {
constructor() {
this.conPromise = mysql.createConnection({
host: "localhost",
user: "XXX",
password: "XXX",
database: "APP"
});
}
async GetClients() {
const con = await this.conPromise;
const result = await con.query("SELECT * FROM contacts");
console.log(result);
return result;
}
}
Finally, you'd use that class as follows:
router.get('/Clients' , async (req , res) => {
let sql_getter = new SqlDataGetter();
const clients = await sql_getter.GetClients();
console.log(clients);
res.status(200);
res.send({ respond : clients});
});