Filter LookUp Field

Filter LookUp Field

Hello,
I would like to filter lookup field using Deluge i tried doing it using below code but it just clears the records in the field it doesn't filter the records.

Code:
for each  rec in Product_Master[Units.contains("Mtr") && ID != 0]
{
match = count(Product_Master[Units.contains("Mtr") && ID != 0]);
if(match>0)
{
input.Product_Master:ui.add(rec.Design_No);
}
}

//Units is the Drop Down Field