Custom field lock down

I have a custom drop down list from a User Code. I don’t want them to be able to type in the field just select the drop down. How can I do this?

Thanks

There may be a way to enforce this from the UI, but, a BPM could be used.

Basic logic.

Pre-processing method directive on the appropriate .update method.

Condition:
the {bound field} of the changed row is not equal to ‘’
and the {bound field} of the change row can’t be found in usercode.[field]

if true then

Action:
raise exception.

The ABL for that would look something like:

FOR EACH ttTABLE WHERE tt[TABLE].RowMod = 'U' OR tt[TABLE].RowMod='A',
  FIRST udcode WHERE tt[TABLE].[boundfield]=udcode.[FIELD] no-lock:
  IF NOT AVAILABLE udcode THEN DO:
    {lib\PublishEx.i &ExMsg = "'invalid value in XYZ field.  Please select value from drop down'"}
    {&THROW_PUBLIC}.
  END.
END.

Thanks this is what worked for me…

EpiComboBox1.DropDownStyle = Infragistics.Win.UltraWinGrid.UltraComboStyle.DropDownList;