Stopping Formview insert command button - too late to trigger isvalid=false ??? viewstate lost after

[Jason]

I'm reading that this is by design.. but It's just killing me.

I see all sorts of nice events - onclick, onupdating, onupdating .. I
can cancel the update with e.cancel etc... Great.

So why can't I stop the formview from posting and return back to my
page with all my viewstate data intact so the users can correct any
NON-VALIDATION issue and re-attempt to update?

Why do I need this? Say I want to bounce some of my data against
another table, or say I've got some crazy function or logic that just
don't fit into the validators and I want to trip the form so that It
doest not post, where can I do this If I'm using sqldatasource for
update/insert ?

Thanks.