How to make a custom property with multiple fields in Bitrix?

Question

1C-Bitrix

OnIBlockPropertyBuildList has a GetPropertyFieldHtmlMulty method . But I don't quite understand how to save multiple fields. It turns out with only one:

AddEventHandler("iblock", "OnIBlockPropertyBuildList", array("CIBlockPropertyCustom", "GetUserTypeDescription"));
class CIBlockPropertyCustom
{
    public function GetUserTypeDescription()
    {
        return array(
            "PROPERTY_TYPE"        => "F",
            "USER_TYPE"            => "SERVICE",
            "DESCRIPTION"          => "Фотогалерея",
            "GetPropertyFieldHtml" => array("CIBlockPropertyCustom", "GetPropertyFieldHtml"),
        );
    }

    public static function GetPropertyFieldHtml($arProperty, $value, $strHTMLControlName)
    {
        return '<input type="text" name="'.$strHTMLControlName["VALUE"].'" value="'.$value['VALUE'].'">';
    }
}

As a result, I need to save two fields: a file and a text field

Answer 1

File is a number. The second field is a string.
To store 2 separate values ​​in one database field, you need to develop your own data serialization method.
To modify values ​​before saving to the database and after reading from the database, additionally describe the ConvertToDB and ConvertFromDB methods, respectively.
PS
One more option: write the text part of the property value as DESCRIPTION to the saved file (when you execute the CFile::Save method).

Answer 2

I have not worked with this functionality for a long time, it should be the same as with one, only in the second parameter there will be not one value, but an array of values. js for the "Add" button also seems to need to be written by yourself.