SelectedValueChanged event is giving me a headache

SQLScott · December 22nd, 2007, 09:05 PM

I am running into an issue that I would have thought wouldn't be difficult, but for some reason I am drawing a blank, and frankly am embarassed to ask (must be all the eggnog...).

I have a form with a button and two list boxes. The button populates the first list box with data.

On the SelectedValueChanged event of the first list box I have code which populates the second list box.

The problem I am running in to is that the code in the SelectedValueChanged event of the first list box is being fired as soon as I set its DataSource.

In the click event of the button, I create and populate a Dataset and set that as the data source of the first list box. In the SelectedValueChanged of the first list box, I have code similar to the following:

If Me.listbox1.SelectedIndex > -1 Then
id = directcast(me.listbox1.selectedvalue, integer)
'do other stuff
end if

The problem I am having is that because the SelectedValueChanged is being called as soon as I set the DataSource, the SelectedValue has a value of System.Data.DataRowView, and therefore the setting of my id variable is blowing.

What am I doing wrong? Any insight is greatly appreciated.

========================
Scott Klein
Author of:
Professional SQL Server 2005 XML
Professional WCF Programming: .NET Development with the Windows Communication Foundation
Professional LINQ
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BrianWren · January 2nd, 2008, 06:46 PM

In the routine that is populating the 1st listbox, set a module/class-scope boolean to True:

Code:

    bUpdatingList = True

In the routines that are running when they ought not, add

Code:

    If bUpdatingList = True Then Exit Sub

Of course, when the list gets filled, the first element becomes current. That represents a change of SelectedValue, which in turn raises the event...

Or am I missing the specifics of the problem?

(Had to edit to fix spelling...:()