PHP validator borrowed from Lavarel.
composer require ark/validator
<?php
use Ark\Validator\Validator;
$validator = new Validator($form, [
'email' => 'required|email',
'password' => 'required|length_between:8,20'
]);
if (!$validator->valid()) {
echo $validator->errors()->first();
} else {
echo 'success';
}