need help with cascading asp:dropdownlist

PederSvaleng posted on Wednesday, December 23, 2009

I've been searching all day but without luck.
I have an asp FormView with two dropdownlists RegionGovernor and SchoolOwner. When I change the index of RegionGovernor I would really like the SchoolOwner dropdownlist to repopulate itself.
My code looks like this:

protected void RegionGovernorNameValueListDataSource_SelectObject(

         object sender, Csla.Web.SelectObjectArgs e)

      {

         e.BusinessObject = RegionGovernorNameValueList.GetList();

      }

      protected void SchoolOwnerNameValueListDataSource_SelectObject(object sender, Csla.Web.SelectObjectArgs e)

      {

         string id = ((DropDownList)SchoolFormView.FindControl("RegionGovernorDropDownList")).SelectedValue;

         int regionGovernorId;

         int.TryParse(id, out regionGovernorId);



         e.BusinessObject = SchoolOwnerNameValueList.GetList(regionGovernorId);

      }     



      protected void RegionGovernorDropDownList_SelectedIndexChanged(object sender, EventArgs e)

      {

         SchoolFormView.UpdateItem(false);

      }

When I change DDL1 (RegionGovernor) RegionGovernorDropDownList_SelectedIndexChanged throws exception:
'SchoolOwnerDropDownList' has a SelectedValue which is invalid because it does not exist in the list of items.

Any ideas how I can do this? Thanks