Populate list from recordset on Parent/Child form

Question

We have a parent/child form and want to populate several lists from recordsets. We can populate the child canvas by calling a procedure from the WHEN NEW FORM INSTANCE trigger but the same code fails when trying to populate a list on the Parent canvas. If I move the code to a PRE-BLOCK trigger on the parent block, then it works. I just kept moving the code until I found something that works. Can anyone tell me why it wouldn't work from the WHEN NEW FORM INSTANCE trigger? Is PRE-BLOCK the correct place?

Answer 1

WHEN-NEW-FORM-INSTANCE trigger
Add_Orgs_Lists('HR_PERSONS.OFFICE_SYMBOL');
PROGRAM UNIT
PROCEDURE Add_Orgs_Lists (list_name VARCHAR2) is list_id ITEM;
     col_name VARCHAR2(80) := SUBSTR(list_name, INSTR(list_name, '.')+1);
     sql_stat VARCHAR2(2000);
     BEGIN
     --Find ID for list item.
          list_id := FIND_ITEM(list_name);
          IF ID_NULL(list_ID) THEN
               MESSAGE('List Item ' ||list_name|| ' does not exist.');
               RAISE FORM_TRIGGER_FAILURE;
          END IF;
     --Build the SQL statement.
     --     message('In Get_Org');
     sql_stat := 'SELECT Distinct Org_Name, Org_Name FROM HR_Organizations
     ORDER BY 1 ASC';
     Populate_the_List(list_id, sql_stat);
          EXCEPTION
               WHEN OTHERS THEN
                    MESSAGE('Internal error occurred in Add_Orgs_List.');
                    RAISE FORM_TRIGGER_FAILURE;
END Add_Orgs_Lists;
PROCEDURE Populate_the_List (list_id ITEM,
                                                       sql_stat VARCHAR2) is
     group_id RecordGroup;
     outcome NUMBER;
     --List_Elements  VARCHAR2(40);
BEGIN
          --message('In Populate_the...');     
--Create temporary record group.
group_id := CREATE_GROUP_FROM_QUERY('List_Elements', sql_stat);
IF ID_NULL(group_id) THEN
     MESSAGE('Record Group could not be created in Populate_the_List.');
     RAISE FORM_TRIGGER_FAILURE;
END IF;
--Populate record group.
     outcome := POPULATE_GROUP(group_id);
     IF outcome <> 0 THEN
          MESSAGE('Record Group could not be populated in Populate_the_List.');
          RAISE FORM_TRIGGER_FAILURE;
     END IF;
--Populate list item
     POPULATE_LIST(list_id, group_id);
--Destroy the temporary record group to release resources
     DELETE_GROUP(group_id);
EXCEPTION
     WHEN OTHERS THEN
     MESSAGE('Internal error occured in Popluate_the_List.');
     RAISE FORM_TRIGGER_FAILURE;
END Populate_the_List;
The error is FRM-41337 Cannot populate the list from record group. It happens when we open the form. We are using the same code to populate the lists on the child form (except the SQL statement is different) and it works correctly.
I appreciate your help.