Async handling issue in nodejs - node.js

Question

I am new in nodejs. I am creating a basic API to get record by id. Everything is working fine. It is returning user data from database. But when i use password variable from response in same function it give me empty value whereas i am getting value in response. I think this is async issue but i dont know how to fix it.
This is API code
var express = require('express');
var db = require('../db/database');
var bcrypt = require('bcrypt');
const router = express.Router();
router.get("/:userId", (req, res, next) => {
let uid = req.params.userId;
db.query(`SELECT * FROM users WHERE u_id = ${uid}`, (err, data)=> {
if(!err) {
if(data && data.length > 0) {
var message = '';
if(data.u_password){
//var pass = data.u_password;
if(bcrypt.compare('123456', data.u_password)) {
// Passwords match
message = 'Passwords match';
} else {
// Passwords don't match
message = 'Passwords dont match';
}
}
res.status(200).json({
message:message,
});
} else {
res.status(200).json({
message:"User Not found."
});
}
}
});
});
database.js
var mysql = require('mysql');
const pool = mysql.createPool({
connectionLimit : 10,
host: 'localhost',
user: 'root',
password: '',
database: 'lost_and_found',
debug : false
});
function executeQuery(sql, callback) {
pool.getConnection((err,connection) => {
if(err) {
return callback(err, null);
} else {
if(connection) {
connection.query(sql, function (error, results, fields) {
connection.release();
if (error) {
return callback(error, null);
}
return callback(null, results);
});
}
}
});
}
function query(sql, callback) {
executeQuery(sql,function(err, data) {
if(err) {
return callback(err);
}
callback(null, data);
});
}
module.exports = {
query: query
}
Response
{"message":""}

Answer 1

Please change the bcrypt.compare code to following code. It is a callback function:
bcrypt.compare('123456', data.u_password, function(err, result) {
if (err) {
// Passwords don't match
message = 'Passwords dont match';
} else {
// Passwords match
message = 'Passwords match';
}
res.status(200).json({
message:message,
});
})
EDIT 1: Please update the method to following logic:
db.query(`SELECT * FROM users WHERE u_id = ${uid}`, (err, data) => {
if (err) {
throw err;
}
if (data && data.length > 0) {
var message = '';
if (data.u_password) {
bcrypt.compare('123456', data.u_password, function (err, result) {
if (err) {
// Passwords don't match
message = 'Passwords dont match';
} else {
// Passwords match
message = 'Passwords match';
}
res.status(200).json({
message: message,
});
})
}
res.status(200).json({
message: "User Not found."
});
}
res.status(200).json({
message: "User Not found."
});
});