Laravel Validation: Custom Rules and Messages

Advanced validation techniques:

Custom Rule Class

class Uppercase implements ValidationRule
{
    public function validate(string $attribute, mixed $value, Closure $fail): void
    {
        if (strtoupper($value) !== $value) {
            $fail('The :attribute must be uppercase.');
        }
    }
}

Use Custom Rule

$request->validate([
    'name' => ['required', new Uppercase],
]);

Custom Messages

$messages = [
    'email.required' => 'We need your email address.',
];
$request->validate($rules, $messages);