Advice needed on the Drop-down box description.

Question

There are lots of postings on how to get the drop-down box working and there's even a How-to guide called Dropdown boxes. However, I have a field (defined using the AET tool) which has an Search help assigned, so the drop-down list is automatically displayed for me. Having said that I'm still bemused as to how it works as there's no code in the P and V Getter methods.
Anyway, that aside, the dropdown box is working fine, as mentioned, but I also have the description field to populate with the description of the value returned by the drop-down box. In my case it's a Department code and associated description.
Initially, I inserted code in the SET_DEPT method to lookup the description (using a SELECT statement) and place the result in the DEPT_DESC field. However, this method is not being called, I don't think, or at least my break point is not being reached.
So I'm looking for somewhere to place the code which will be called when the DEPT field changes value, and I can then lookup the description and populate the DEPT_DESC field.. Both the DEPT and DEPT_DESC fields are in the same context node by the way.
It's a real pity that when you create new fields in the AET tool you can't relate one field to another or somehow use a search help and say that the source is another field and this field will hold the result, or something like that.
Jason

Answer 1

Hi,
It was said that the SET_* method will be called when you press enter on the view to trigger a server round trip.
For your case, I'd like to suggest you take standard coding for example.
That is the categorization in service ticket view in IC_AGENT role.
When select the first category, if the second category only has one value, it will be automatically set. which should be similar to your requirement.
component view GSMCDDLB/DropDownList
call stack is
METHOD SET_FIELDS      CL_GSMCDDLB_DROPDOWNLIST_IMPL=CP
METHOD EH_ONCATCHANGE  CL_GSMCDDLB_DROPDOWNLIST_IMPL=CP
METHOD DO_HANDLE_EVENT CL_GSMCDDLB_DROPDOWNLIST_IMPL=CP
when a value is selected in the first dropdown, an event is triggered, you may debug and find out your event, and make the codings in EH_* method.
set value for other field is some what simple also, like that in
METHOD SET_FIELDS      CL_GSMCDDLB_DROPDOWNLIST_IMPL=CP
CALL METHOD lr_dropdownlist->if_bol_bo_property_access~set_property
If the first field is not a dropdown, for example a field with F4 help, after select the value from the popup, there will be event SELECT_OBJECT triggered for the view I tested.
You may put breakpoint in do_handle_event for the controller class and observe what event was triggered.
Then make the relevant coding.
Hope could do help!
Hongyan