Cannot Change the Display Type Property of New Extension Field

[former_member27015]

I created an extension object to extend a standard object CustomerRequirement like so;

import AP.Common.GDT;
import AP.SupplyChainControl.Global;
[Extension] businessobject AP.SupplyChainControl.Global:CustomerRequirement {
        // You must activate this business object before you can access the extension fields
        // or messages in script files, forms, and screens.
[Label ("Ship-from Location")] element ShipFromLocation : String;
[Label ("Reason for Transfer")] element TransferReason : String; 
}

On the UI Designer, I'm unable to change one of the fields to a dropdownlist as required. I tried to change it from the display type property but it just returns to TextEdit. How can I change it to a dropdownlist please?

I am using version 1908.

[VVancalbergh · Accepted solution]

String is a datatype that does not support dropdowns (what would the allowed values be?).

You either define your own codelist datatype where you set the allowed values and use that codelist as datatype for your element or you use one of the existing codelist datatypes.