i want to add new item using inline add,
after click add button, inline autocomplete field show 'undefined'.
but if i insert using popup add, field is empty (not 'undefined')

i want inline autocomplete show empty field, so i can input right away without removing 'undefined' text first.
i can use $col2["editoptions"] = array("defaultValue"=>' '); to override the undefined text, but i cant assign either '' or null to default value, so i have to put white space to tricked it, but it still not an empty value.

here's my col code:

$col2 = array();
$col2["title"] = "Item Name"; // caption of column
$col2["name"] = "purchase_request_item_name"; // grid column name, must be exactly same as returned column-name from sql (tablefield or field-alias)
$col2["search"] = true;
$col2["width"] = "7";
$col2["show"] = array("list"=>true, "add"=>true, "edit"=>true, "view"=>true);
$col2["editable"] = true;
$col2["formatter"] = "autocomplete"; // autocomplete
$col2["formatoptions"] = array("sql"=>"SELECT
item_packing_id,
item_original_id,
item_original_code,
item_original_name,
(
SELECT
item_hs_code
FROM
item b
WHERE
b.item_id = a.item_original_id
) as item_hs_code,
item_packing_detail_measurement,
item_packing_detail_uom_id,
item_packing_detail_uom,
item_packing_original_id,
item_packing_original,
(SELECT item.item_hs_code FROM item WHERE item_id=item_original_id)AS item_hs_code,
CONCAT('(',item_original_code,') ',item_original_name,' (',item_packing_detail_measurement,' ',item_packing_detail_uom,'/',item_packing_original,' )') as v FROM item_packing a
WHERE item_packing_record_status = 'A' AND item_packing_company_id = '$_SESSION[user_company_id]' AND item_packing_is_discontinue <> '1'",
"search_on"=>"CONCAT(item_original_code,' ',item_original_name)","callback"=>"fill_form_item", "update_field" => "purchase_request_item_name");
$col2["editrules"] = array("required"=>true);
$cols2[] = $col2;