Filter Options in Select Field - Not Working


I have two fields:

  • First is called Item Intention, which has the field name custom_item_purpose
  • Second is called Usage Classification, which has the field name custom_usage_classification

Item Intention has two options, “To Manufacture” and “To Purchase”. Depending on the selection I want to remove the option “Sundry” from the “Usage Classification” select dropdown.

I am trying to follow the example given in the docs (the example of which seems to have errors as it’s missing a comma after the set_field_options)
But it is not working, all options appear in the “Usage Classification” field regardless of choice.

Code is below, can anyone see where I am going wrong?

  if(frm.doc.custom_item_purpose == "To Manufacture") {
    set_field_options("Usage Classification", ["Development","Investigation","Production"]);
  else if(frm.doc.custom_item_purpose == "To Purchase")
    set_field_options("Usage Classification", ["Development","Investigation","Production","Sundry"]);
  else if(frm.custom_item_purpose == "")
    set_field_options("Usage Classification", ["Development","Investigation","Production","Sundry"]);

I had tried replacing Usage Classification with custom_item_purpose in the code but it didn’t seem to make any difference.