Part 5: Create your own Registration System using PHP and MySql

5. Validating Form Data

We already have basic validation in our PHP script but what if we want to check if the email is actually an email or if the username and password should be a certain amount of characters long, you can do that with the codes below, add them in the register.php file before the following line:

if ($stmt = $con->prepare('SELECT id, password FROM accounts WHERE username = ?')) {

 

Email Validation

if (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) {
	exit('Email is not valid!');
}

 

Invalid Characters Validation

if (preg_match('/^[a-zA-Z0-9]+$/', $_POST['username']) == 0) {
    exit('Username is not valid!');
}

 

Character Length Check

if (strlen($_POST['password']) > 20 || strlen($_POST['password']) < 5) {
	exit('Password must be between 5 and 20 characters long!');
}

You should always implement your own validation, these are just basic examples.