September 28^th 2005

Selecting nothing in a ComboBox #2

It's been more than a month since discovering that to set "nothing" as the selection in a combo box the code needed doing twice (see here). But there was more to this .NET issue than met the eye - and once testing got underway it soon became apparent that the combo box would suffer if the database it was bound to had a null entry. Not too easy to describe (so I wrote a short VB program to demonstrate it (see here) - what happens is that the combo box selects the first item in the list instead of nothing. So when "scrolling" through records the combo box will at times show a value when it shouldn't.

Again this turns out to be a known issue - and the answer is to add a row to the data in the combo box with a null value, and text like "please select a value" (or blank if the user is allowed to select nothing...). I have to admit that actually having that entry there explicitly is quite nice - but that's not the point - it should have worked the other way... Fixed in VS 2005?