When you create an Application Computation and set it to run "On New Instance (i.e. Login)", APEX doesn't yet have the APP_USER in session state.
I have an application where depending on the current user, many application-wide variables should be initialized. If I cannot access the APP_USER item, this cannot be done by using an Application Computation.
My alternative is to create Page Computations for the application items on Page 1 (or whatever the default page is after logging on).
We're already using VPD but there are some aspects of the system that have to be limited in the front-end rather than at the database level so that doesn't help my problem, but thank you for the suggestion.
The problem is simple, the value of APP_USER is inaccessable at the time when an application computation is run if that application computation is setup to run "On New Instance (i.e. Login)".
I've tried v('APP_USER'), :APP_USER and &APP_USER., and all return null, whether I use them in a SQL statement or even as Static Assignment.