I have two related RadComboBoxes as following:
<telerik:RadAjaxManagerProxyID="RadAjaxManager1"runat="server"> <AjaxSettings> <telerik:AjaxSettingAjaxControlID="RadDropDownParameterX"> <UpdatedControls> <telerik:AjaxUpdatedControlControlID="RadComboBoxCountries"LoadingPanelID="AjaxLoadingPanel1"/> <telerik:AjaxUpdatedControlControlID="RadComboBoxSites"LoadingPanelID="AjaxLoadingPanel1"/> <telerik:AjaxUpdatedControlControlID="RadComboBoxRts"LoadingPanelID="AjaxLoadingPanel1"/> <telerik:AjaxUpdatedControlControlID="RadComboBoxMachines"LoadingPanelID="AjaxLoadingPanel1"/> <telerik:AjaxUpdatedControlControlID="RadComboBoxProtocols"LoadingPanelID="AjaxLoadingPanel1"/> </UpdatedControls> </telerik:AjaxSetting> <telerik:AjaxSettingAjaxControlID="RadComboBoxCountries"> <UpdatedControls> <telerik:AjaxUpdatedControlControlID="RadCodeBlock1"LoadingPanelID="AjaxLoadingPanel1"/> <telerik:AjaxUpdatedControlControlID="RadCodeBlock2"LoadingPanelID="AjaxLoadingPanel1"/> <telerik:AjaxUpdatedControlControlID="RadComboBoxSites"LoadingPanelID="AjaxLoadingPanel1"/> </UpdatedControls> </telerik:AjaxSetting> ...</telerik:RadAjaxManagerProxy>...<telerik:RadAjaxLoadingPanelID="AjaxLoadingPanel1"runat="server"Skin="BlackMetroTouch"></telerik:RadAjaxLoadingPanel>...<divclass="right"> <span>Select X-parameter</span> <telerik:RadDropDownListID="RadDropDownParameterX"runat="server" DropDownHeight="120px"Width="120px"Skin="BlackMetroTouch"DropDownWidth="120px" OnSelectedIndexChanged="RadDropDownParameterX_SelectedIndexChanged" AutoPostBack="true"> <Items> <telerik:DropDownListItemText="Countries"Value="Countries"Selected="true"/> <telerik:DropDownListItemText="Sites"Value="Sites"/> <telerik:DropDownListItemText="Rts"Value="Rts"/> <telerik:DropDownListItemText="Machines"Value="Machines"/> <telerik:DropDownListItemText="Protocols"Value="Protocols"/> </Items></telerik:RadDropDownList>... <divclass="combo countries"> <telerik:RadComboBoxID="RadComboBoxCountries"runat="server" AutoPostBack="True" onselectedindexchanged="RadComboBoxCountries_SelectedIndexChanged" CheckBoxes="true"EnableCheckAllItemsCheckBox="true" Label="Country"Skin="BlackMetroTouch"> </telerik:RadComboBox> <divclass="subv"><telerik:RadCodeBlockID="RadCodeBlock1"runat="server"> <%= SelectedCountriesText %></telerik:RadCodeBlock></div></div> <divclass="combo sites"> <telerik:RadComboBoxID="RadComboBoxSites"runat="server" CheckBoxes="true" AutoPostBack="true" onselectedindexchanged="RadComboBoxSites_SelectedIndexChanged" EnableCheckAllItemsCheckBox="true" Label="Site"Skin="BlackMetroTouch"> </telerik:RadComboBox> <divclass="subv"><telerik:RadCodeBlockID="RadCodeBlock2"runat="server"> <%= SelectedSitesText %></telerik:RadCodeBlock></div></div> What i am trying to achieve is to have the second comboBox (RadComboBoxSites) populated upon selected Values of first comboBox.
Tried to achive that by deleting all items of RadComboBoxSites each time a SelectedIndexChanged event is occured on comboBox RadComboBoxCountries in the way depicted below:
ProtectedSubRadComboBoxCountries_SelectedIndexChanged(ByValo AsObject, ByVale AsTelerik.Web.UI.RadComboBoxSelectedIndexChangedEventArgs) If(RadDropDownParameterX.SelectedValue.Equals("Sites")) DimcollectionPopulatedSites = RadComboBoxSites.Items Foreach s IncollectionPopulatedSites DimRadComboBoxSite AsRadComboBoxItem = RadComboBoxSites.Items.FindItemByValue(s.Value) IfRadComboBoxSite IsNot NothingThen RadComboBoxSite.Remove EndIf Next ' get new list of selected countries DimcollectionSelectedCountries = RadComboBoxCountries.CheckedItems Foreach c in collectionSelectedCountries DimlistaCountrySites AsList(Of AffideaGeneralWeb.BLL.General.Sites) listaCountrySites = GetAllCountrySites(c.Value) Foreach s in listaCountrySites DimRadComboBoxSite AsRadComboBoxItem = RadComboBoxSites.Items.FindItemByValue(s.ID) IfRadComboBoxSite IsNothingThen RadComboBoxSite = NewRadComboBoxItem() RadComboBoxSite.Text = s.Title RadComboBoxSite.Value = s.ID RadComboBoxSites.Items.Add(RadComboBoxSite) EndIf Next Next EndIfEndSubHowever when i am trying to "RadComboBoxSite.Remove" i am getting an exception:
An exception of type 'System.InvalidOperationException' occurred in mscorlib.dll but was not handled in user code. Additional information: The collection has changed, the enumeration operation may not be performedIs there any working example of related comboBoxes (handles in the server side)?
How could i delete all items of second comboBox and re-build it, each time the user alters selection on the first comboBox?