Custom fields from code

Custom fields from code

How do you reference custom fields on invoice items in code in Zoho Books?

I tried the following code but it failed when it tried to convert the custom field list to a list.

    lineItems = invoice.get("line_items").toList();
    for each  item in lineItems
    {
     item_CFs = item.get("custom_fields").toList();
     for each  item_cf in item_CFs
    {
     msg = msg + item_cf.get("value").toString();
        }
     }