Prevent Deletion of RadListBoxItem

[G.]

Hello,

Telerik.Web.UI Version 2010.3.1317.35

I have 2 RadListBox controls defined as follows:

 

 

<div id="dFieldSelection" style="padding:5px;" runat="server">

 

 

 

<telerik:radlistbox runat="server" DataTextField="Name" DataValueField="FieldID" ID="radListBox_1" AllowDelete="True"

 

 

 

AllowReorder="True" AllowTransfer="True" AutoPostBackOnTransfer="true" AutoPostBackOnDelete="true" TransferToID="radListBox_2">

 

 

 

</telerik:radlistbox>

 

 

 

<telerik:radlistbox runat="server" ID="radListBox_2"

 

 

 

AutoPostBackOnTransfer="true" AutoPostBackOnDelete="true"

 

 

 

ondeleting="radListBox_2_Deleting"></telerik:radlistbox>

 

 

 

</div>

I programmtically place some mandatory fields into radListBox_2...  my goal is to prevent a user from deleting these mandatory items from radListBox_2 (i.e. I have noticed that the radListBox_2_Deleting server side event get executed when the user presses the arrow button to transfer an item back to radListBox_1).

Inside of radListBox_2_Deleting server side event I simply do some code checks and if this is a mandtory item I set e.Cancel = true... hoping that that will cancel the deletion.  However, this does not appear to work as I expected.

How can I prevent a user from moving 1 RadListBoxItem from radListBox_2 back into radListBox_1?

Thx in advance!!!

 

[Bozhidar]

Hello Gerald,

You can use the OnClientTransferring event and check if the source listbox is the one you don't want to delete from. If it is, then you can use args.set_cancel(true) to cancel the transfer. Here's an example:

function clientTransferring(sender, args) {
    var listbox = $find("<%= radListBox_2.ClientID %>");
    if(args.get_sourceListBox() == listbox)
        args.set_cancel(true);
}

 
All the best,
Bozhidar
the Telerik team