reference selector widget

Hi, I am a starter of Mendix. I want an easy solution to avoid duplicate entries of a assocation  with these input widget. Such as a reference is list of Strings in database. Based on what already has been selected of one of more items out of the associated list, these should be not be viewed or denied afterwards (by microflow?)   Regards Wim      
1 answers

Hey Wim, 

my idea would be to add to add a second reference between Detailssystempart and system. (Maybe call them “open” and “locked”).

That way you can display all objects that are still open for selection and in after selection, switch your reference to locked. Then it should not be displayed anymore.