UuidRule.php

<?php

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class UuidRule implements Rule
{
    public function passes($attribute, $value)
    {
        return preg_match("/[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/", $value);
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        return 'Invalid Uuid.';
    }
}