How does the RadComboBox handle nulls?

[Rod]

I've discovered something about the out-of-the-box WPF ComboBox. It apparently doesn't handle nulls coming from the database very well. If there's a null in the database, and you do something like this:

<ComboBox x:Name="cmbMajorProbByInterviewer"
          VerticalAlignment="Top"
          ItemsSource="{Binding Source={StaticResource aSICodesSubstanceTypeViewSource2}}"
          DisplayMemberPath="SubstanceDesc"
          SelectedValue="{Binding MajorProblemByInterviewer}"
          SelectedValuePath="SubstanceType"
          Grid.Column="3" />

then it's my experience that if there's a null for the MajorProblemByInterviewer, what the combo box will show is the first item in the items source coming from aSICodesSubstanceTypeViewSource2. That is not what I want.

So I'm wondering, does Telerik's RadComboBox show nothing (i.e.: SelectedIndex == -1) if the value coming from the database is null?

[Rosen Vladimirov]

Hello Rod,

I'm not sure I fully understand what is the desired effect and how the ComboBox selects the first item (I've tried to reproduce this behavior with both RadComboBox and default ComboBox, but I couldn't). Anyway I've prepared a sample project demonstrating my approach - could you give it a try and inform us in case you have any problems or concerns.

Regards,
Rosen Vladimirov
Telerik