warehouse/app/Validation/Rule/PositiveIntegerRule.php

<?php

namespace App\Validation\Rule;

use Framework\Validation\Rule\Rule;

class PositiveIntegerRule implements Rule
{
    public function validate(array $data, string $field, array $params)
    {
        if (empty($data[$field])) {
            return true;
        }

        return ctype_digit((string) $data[$field]) && (int) $data[$field] > 0;
    }

    public function getMessage(array $data, string $field, array $params)
    {
        return "{$field} must be a positive whole number";
    }
}