I had the exact same issue as outlined in this SO post: https://stackoverflow.com/questions/61333206/detecting-a-selectinput-value-change-to-null-in-r-shiny
I feel as though the default behavior here, when multiple = TRUE in a selectInput, needs to be observing and handling NULLs better and more explicitly, especially if selected also equals NULL.
I just find it very opaque that the change from 1 selection to NULL is not being registered as a change by observers unless they have been explicitly set to have ignoreNULL set to TRUE--it means many forms of validation will fail silently currently, as checks for NULL won't even occur if they are inside the observers....
I know that to some this "bug" is a "feature," but I think a warning() might at least be justified to give some flag to folks that this is the default behavior.
I had the exact same issue as outlined in this SO post: https://stackoverflow.com/questions/61333206/detecting-a-selectinput-value-change-to-null-in-r-shiny
I feel as though the default behavior here, when multiple = TRUE in a selectInput, needs to be observing and handling NULLs better and more explicitly, especially if selected also equals NULL.
I just find it very opaque that the change from 1 selection to NULL is not being registered as a change by observers unless they have been explicitly set to have ignoreNULL set to TRUE--it means many forms of validation will fail silently currently, as checks for NULL won't even occur if they are inside the observers....
I know that to some this "bug" is a "feature," but I think a warning() might at least be justified to give some flag to folks that this is the default behavior.