ON-ERROR and ON-MESSAGE-trigger

Many developer have problems with messages which popup in forms, for example "FRM-40401: No changes to save".

Then they look for workarounds and one of the easiest is manipulating the :system.message_level:

KEY-COMMIT - trigger on form-level (quick and dirty)

BEGIN
  :System.Message_Level := 25;
  COMMIT;
  :System.Message_Level := 5;
END;

or KEY-COMMIT - trigger

DECLARE
 V_Message_Level NUMBER;
BEGIN
 V_Message_Level := :System.Message_Level;
 :System.Message_Level := 25;
 COMMIT;
 :System.Message_Level := V_Message_Level;
END;

these are not best practices. Because you have to write those codes in hundreds of procedures and tons of code.

Filtering the errors and messages is the key to have a powerful message-handling. Here is an easy procedure which shows you the technique:

ON-ERROR - trigger on form-level

DECLARE
  V_Error_Code       NUMBER;
  V_Error_Text       VARCHAR2 (2000);
  V_DBMS_Error_Code  NUMBER;
  V_DBMS_Error_Text  VARCHAR2 (2000);
BEGIN
  V_Error_Code      := Error_Code;
  V_Error_Text      := Error_Text;
 V_DBMS_Error_Code := DBMS_Error_Code;
  V_DBMS_Error_Text := DBMS_Error_Text;
 
  IF V_Error_Code IN (40401, 40405) THEN
    /*
    || 40401, 40405 - no changes to save / apply  get filtered
    */
    NULL;
  ELSIF V_Error_Code IN (-1034, -3114) THEN
    /*
    || -1034, -3114 - not connected to database
    */
    Message ('Not connect to database, exiting Form');
    Exit_Form (no_validate);
  ELSIF V_Error_Code IN (40508, 40735)
  AND   V_DBMS_Error_Code BETWEEN -20999 AND -20000 THEN
    /*
    || -20000 errors are raised by RAISE_APPLICATION_ERROR 
    || They are handled in a different way
    */
    Show_and_Log_DB_Error (V_DBMS_Error_Text);
  ELSE
    /*
    || All other errors went into Show_and_Log_Error, where they
    || get inspected, analyzed and logged.
    */
    Show_and_Log_Error (V_Error_Code);
  END IF;
END;