Avoiding unhandled error page branching

Question

Hi all,
I was trying to avoid those situations where the user is brought to that spartan error page when an "unhandled" exception occurs, such as a constraint violation.
In such situations one should first check whether an identical unique key is already existing, that is one should write some pl/sql code for the validation and, if it succeeds, let the process insert the new row or return an error otherwise.
However I started to wonder: what about moving my insert process inside the validation and trap the exception there?
So I did, transforming the process (conditional on a certain button) to a conditional pl/sql function returning boolean type of validation and it works just fine.
So, now, instead of displaying that unwelcoming error page, I write an inline notification telling the user that an identical entry is already existing which looks much better.
My only concern was with the commit/rollback behind the scene, but I didn't find problems until now.
What do you think guys?

Answer 1

Scott,
I forgot to mention that most likely this "validation" must occur last, at the very end of the chain of real validations on the fields.
The page where I tested this contains several item validations and three different branches depending on buttons and also the validations are depending on those buttons.
After completing 10 "normal" validations there are these two special validations hooked up to two distinct buttons and they work fine.
Of course it doesn't make sense to execute them upfront, before item validations, it would be a big mistake from the application logic viewpoint.
Last but not least, this way I avoid also a custom validation checking against the primary key and/or unique key(s) by means of a query which would require a very similar approach, either a SQL or PL/SQL custom function.
I mean, not a big deal probably, but the lighter is the burden on the server, the better, isn't it?
Bye,
Flavio