ReferenceError: hash is not defined in node.js

Question

i am making a login system and using bcrypt to hash passwords. But now when i try to login i got this error that says that ReferenceError: hash is not defined.I will be thankful if anyone can help me and tell me where and how to declare hash. This is my login.js code.

var mysql = require('mysql');
var express = require('express');
var session = require('express-session');
var bodyParser = require('body-parser');
var bcrypt= require('bcrypt');
var path = require('path');
var connection = mysql.createConnection({
    host     : 'localhost',
    user     : 'root',
    password : 'sahoolat1',
    database : 'fyp_sahoolat'
});
var app = express();
app.use(session({
    secret: 'secret',
    resave: true,
    saveUninitialized: true
}));
app.use(bodyParser.urlencoded({extended : true}));
app.use(bodyParser.json());
app.get('/', function(request, response) {
    response.sendFile(path.join(__dirname + '/welcome.html'));
});
app.post('/auth', function(request, response) {
    var number = request.body.number;
    var password = request.body.pwd;
    
    if (number && password) {
        bcrypt.compare(password, hash, function(err, result) {
        connection.query('SELECT fyp_helpers.Mobile_number AS number FROM fyp_helpers WHERE Mobile_number = ? AND Password = ? UNION SELECT fyp_employers.Employer_Contact AS number FROM fyp_employers WHERE Employer_Contact = ? AND Employer_Password = ?', [number, password, number, password], function(error, results, fields) {
            if (error) {
                console.error("An error occurred:", error);
                response.send('Oops, something went wrong!');
            } else if (results.length > 0) {
                request.session.loggedin = true;
                request.session.number = number;
                response.redirect('/home');
            } else {
                 response.send('Incorrect Username and/or Password!');
            }           
            response.end();
        });

    });
}
        else {
        response.send('Please enter Username and Password!');
        response.end();
    }

});
app.get('/home', function(request, response) {
    if (request.session.loggedin) {
        response.send('Welcome back, ' + request.session.number + '!');
    } else {
        response.send('Please login to view this page!');
    }
    response.end();
});
app.listen(3000);

This is full error :

ReferenceError: hash is not defined
    at C:\Users\palwasha\sahoolat-master\login.js:29:31
    at Layer.handle [as handle_request] (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\route.js:137:13)
    at Route.dispatch (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\index.js:281:22
    at Function.process_params (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\index.js:335:12)
    at next (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\index.js:275:10)
    at jsonParser (C:\Users\palwasha\sahoolat-master\node_modules\body-parser\lib\types\json.js:101:7)
    at Layer.handle [as handle_request] (C:\Users\palwasha\sahoolat-master\node_modules\express\lib\router\layer.js:95:5)

@pramodsingh how to define it or get password from both employer and helper table in order to match from botyh and wherever it matches,it should be logged in — palo, Jun 26 '20 at 12:12
you might have encrypted your password before saving to DB using some KEY. when you retrieve password from DB apply same key to decrypt. — pramod singh, Jun 26 '20 at 12:26
@pramodsingh yes I have encrypted it first and then saved it — palo, Jun 26 '20 at 12:35

Hello World · Accepted Answer · 2020-06-26T12:46:05.497

bcrypt.compare(password, hash, callback)

bcrypt.compare expects 3 parameters

The entered password which is request.body.pwd in your case
The password which you are comparing with request.body.pwd which is usually stored in database
Callback which will be called after comparison

In your case, you are not providing any hashed password that's why the error is showing

Please Check documentation here https://www.npmjs.com/package/bcrypt

I recommend using following code to verify password

    if (number && password) {
    var sql = `SELECT 
            fyp_helpers.Mobile_number AS number,
            fyp_helpers.Password AS  Password
        FROM fyp_helpers 
        WHERE Mobile_number = ? 
    UNION 
        SELECT 
            fyp_employers.Employer_Contact AS number ,
            fyp_employers.Employer_Password AS Employer_Password
        FROM fyp_employers 
        WHERE Employer_Contact = ?`;
    connection.query(sql, [number, number], function (error, results, fields) {
        if (results.length > 0) {
            var hashedPassword = result[0].Password;
            bcrypt.compare(password, hashedPassword, function (cryptErr, cryptResult) {
                if (cryptResult) {
                    request.session.loggedin = true;
                    request.session.number = number;
                    response.redirect('/home');
                } else {
                    response.send('Incorrect Password!');
                    console.log(cryptErr);
                }
                response.end();
            });
        } else {
            response.send('User not registered');
        }
    });
}

Hope this helps

if am supposed to get passwords from database so i should use select ? — palo, Jun 26 '20 at 11:53
I used a static password to compare for example. But you need get get `hash` variable from the database and compare it with `req.body.pwd` — Hello World, Jun 26 '20 at 11:53
Yes, you need to create a select statement to get the hashed password from the database. :) — Hello World, Jun 26 '20 at 11:54
`bcrypt.compare(password, hashedPassword, function (error, result)` there is a variable mismatch in `err` and `error` — Hello World, Jun 26 '20 at 12:43
please check `colsole.log(result)` and see what is happening there — Hello World, Jun 26 '20 at 12:44

ReferenceError: hash is not defined in node.js

1 Answers1