Overtrue\Validation\Validator::validateRequired PHP Method

    protected function validateRequired($attribute, $value)
    {
        if (is_null($value)) {
            return false;
        } elseif (is_string($value) && trim($value) === '') {
            return false;
        } elseif (is_array($value) && count($value) < 1) {
            return false;
        } elseif (in_array($value, $_FILES, true)) {
            return (string) $value['tmp_name'] !== '';
        }
        return true;
    }