Hnadling sql error messages in forms

Question

Hi there,
I have a multi block application. I have a check constraint in the database which checks for value > 0 and not null.
Now in the form if i try to insert/update a null into the column, i get FRM-40735 Onerror raised unhandled exception. When i click on Display error it shows the constraint violated. I want to show the constraint when user clicks on save button i.e commits form.
In the on error trigger, both block and form level i have
DECLARE
     lv_errcod NUMBER := ERROR_CODE;
     lv_errtyp VARCHAR2(300) := ERROR_TYPE;
     lv_errtxt VARCHAR2(800) := ERROR_TEXT;
BEGIN
if lv_errcod = 40509 or 40508 then
          message(' bad update');
else     
Message(lv_errtyp||'-'||to_char(lv_errcod)||': '||lv_errtxt);
     Raise form_trigger_failure;
end if;
END;
I dunno why i get unhandled exception.
Any help is appreciated.
Thanks

Answer 1

I'm not sure what your question is but if it's how to get the same error as
display error, then put in:
display_error in an on_error trigger on the block(s):
for example on_error trigger:
declare
     errnum number := ERROR_CODE;
     errtxt varchar2(80) := ERROR_TEXT;
     errtype varchar2(3) := ERROR_TYPE;
     field_name varchar2(30);
begin
     field_name := substr(:system.trigger_field,instr(:system.trigger_field,'.') + 1);
     mess( 'ERROR ' || field_name || ': ' ||errtxt);
     display_error;
     raise form_trigger_failure;
     end;
**** mess is a routine I include for which you need to define an alert of style NOTE.
PROCEDURE mess (mymess varchar2) is
alert_value number;
BEGIN
set_alert_property('DATA_ALERT',ALERT_MESSAGE_TEXT,
mymess);
     synchronize;
     bell;
     alert_value := SHOW_ALERT('DATA_ALERT');
END;