I have created a listbox where I use an expression for the field to be presented. It may be worth to note that the field has a prefix ('_') that is set to be hidden on the UI (SET hideprefix function). Altough this way my field is presented, I can not choose the option: Always One Selected Value (I select one value, so not selecting anything, where this function of course not works is not an issue). How can I achieve with this field that Always One Selected Value is an option? It's important that it remains hidden.
Thanks for the help in advance!
Hey guys, I could solve the problem.
I renamed the field to name without the '_' prefix. Then I have represented it on the UI on this name. I could than choose always one selected value. After that I renamed the field again to it's original name. Now it is hidden in the current selections box, and also one value is always selected!