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Client-side Selection

Telerik RadTreeList has built-in mechanism for items selection. You can select items either on the client or on the server as per your requirements.

To enable the RadTreeList client-side selection you need to set the ClientSettings.Selecting.AllowItemSelection to true. This will allow you to select an item on mouse click. As a result the OnItemClick,OnItemSelecting and OnItemSelected client-side events of the RadTreeList will be fired so you can perform further actions and handle the item selection in a custom manner.

You can also use the below settings to enable additional modes of the client-side selection:

  • ClientSettings.Selecting.AllowToggleSelection - When set to true (the default value is false) enables you to deselect an item by clicking on one that is already selected.

  • ClientSettings.Selecting.UseSelectColumnOnly - When set to true (the default value is false) prevents users from selecting items on mouse click and forces them to use the TreeListSelectColumn for that purpose.

With RadTreeList you might want to provide the ability for multi-item selection. This is done by setting its AllowMultiItemSelection property to true (its default value is false).And to select a few items at a time, one can use the [Ctrl] and [Shift] keys as in Windows Explorer. Or, in case the AllowToggleSelection property is true, just click on the desired items to select them.

The below sample illustrates a simple usage of the above properties:

<telerik:RadTreeList RenderMode="Lightweight" ID="RadTreeList1" runat="server" AllowPaging="True" DataKeyNames="EmployeeID"
    DataSourceID="SqlDataSource1" ParentDataKeyNames="ReportsTo" AllowMultiItemSelection="True"
        <telerik:TreeListSelectColumn UniqueName="SelectColumn">
        <telerik:TreeListBoundColumn DataField="LastName" HeaderText="LastName" UniqueName="LastName">
        <telerik:TreeListBoundColumn DataField="FirstName" HeaderText="FirstName" UniqueName="FirstName">
        <telerik:TreeListBoundColumn DataField="Title" HeaderText="Title" UniqueName="Title">
        <telerik:TreeListBoundColumn DataField="TitleOfCourtesy" HeaderText="TitleOfCourtesy"
        <telerik:TreeListBoundColumn DataField="City" HeaderText="City" UniqueName="City">
        <Selecting AllowItemSelection="true" AllowToggleSelection="true" />
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
    SelectCommand="SELECT [EmployeeID], [LastName], [FirstName], [Title], [TitleOfCourtesy], [City], [ReportsTo] FROM [Employees]">

Note that when client-side selection is enabled through the AllowItemSelection property, theTreeListSelectColumn selects the items on the client. If the AllowItemSelection property is false,server-side selection is performed.

For a live demo illustrating the client-side items selection functionality, follow this link.

When recursive selection is enabled (AllowRecursiveSelection="true"), client selection is disabled and selection is done on the server with a .Rebind(). This can result in loss of user input because of the rebind operation, so you may want to implement the recursive selection on the client as shown in the following code library sample Recursive selection on the client when paging is disabled.

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