Using ADF Security user in role context to change field value

Question

Hi I was wondering if it was possible to change an input text field value depending on the ADF authentication login values.
So if the user in role is manager value is dino2dy if it's Boss its Frank Nimphius.
My idea is that I want the field user to be read only so no one could change it, but since it's a foreign key in the table I need to have values in it for committing to the database.
Since different users will be accessing the application I want every user to have his user name automatically entered into a read only field. Then commit that value into the database.
I have ran into some problems so far, as if I put in a straightforward value in a field, and make it read only, when committing I get an error User field needed. As if the field is empty even though I can see the value on the page.
Hope you guys can help

Answer 1

Yeah I have tried that but I can only use it for true or false values, I do not know how to use it to change a value. I ve used it to make something read only or disabled depending on the user in role.
It still wont work if I change the value in the field. It has to be the database value thing in there. As soon as I change it it starts giving me the you need Korisnik error. But I cant put it as a default value in the database because it defeats the purpose.