I am getting this fatal error: uncaught error: call to a member function real_escape_string() on null , though my code seems ok, on the username part.

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<body class="hold-transition login-page">
<?php
  require('db.php');
  session_start();
    
    if (isset($_POST['username']))
    {
        $username = $_POST['username'];
        $password = $_POST['password'];

        $username = stripslashes($username);
        $username = $mysqli->real_escape_string($username);

        $password = stripslashes($password);
        $password = $mysqli->real_escape_string($password);

        
        $query = "SELECT * FROM `user` WHERE username='$username' and password='$password'";
        $result = $mysqli->query($query) or die($mysqli->error);
        $rows = $result->num_rows;

What I have tried:

i actually converted the code from mysql to mysqli.

Posted 28-Nov-22 3:38am

Rafael Sampayan

Updated 28-Nov-22 4:19am

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Comments

Chris Copeland 28-Nov-22 9:44am

That error means that it cannot find a variable named $mysqli. You may have converted your code and forgotten to rename some variables?

Richard Deeming 29-Nov-22 4:22am

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation/interpolation to build a SQL query. ALWAYS use a parameterized query. PHP: SQL Injection - Manual[^]

Richard Deeming 29-Nov-22 4:23am

Also, you are storing your users' passwords in plain text. Don't do that, unless you want a multi-million dollar fine for not securing your users' data properly!

Secure Password Authentication Explained Simply[^]

PHP: password_hash[^]
PHP: password_verify[^]

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Richard MacCutchan · Answer 1 · 2022-11-28T04:19:00

Solution 1

The variable $mysqli must be a created instance of the mysqli class. See PHP: Dual procedural and object-oriented interface - Manual[^] for details.

Posted 28-Nov-22 4:19am

Richard MacCutchan