Block Multiple Instance Of Form

Question

Hai all,
In forms 6i, can we block the opening of a single form in multiple instances in the same application?
Regards,
Manu

Answer 1

Easy. Use the database.
In the new-form-instance trigger, obtain a lock on an object. If you can't get the lock, then the form is already running so issue and exit.
Since the PL/SQL engine in forms 6i is older, I believe I solved this with a stored procedure in the database:
function obtain_lock return boolean is
l_row mytable%rowtype;
begin
select * into l_row
from mytable
for update no_wait;
return true;
exception when others then -- this is poor, catch the exact error
return false;
end;
The trick then, is to be careful with commit/rollback. If you complete your transaction, someone else can get in the form, so you may want to be careful and either only commit/rollback when user is leaving the form or be quick about re-obtaining your lock any time you commit/rollback.