Question

How do I populate a listbox that is located in the InsertItemTemplate? I need to poplulate this after someone clicks the add new record button and I need to do this in the code behind after they click.

Answer 1

There are few ways of doing it. I prefer Template Edit Form. Here is the sample.

<telerik:RadGrid ... OnItemDataBound="RadGrid1_ItemDataBound">
   <MasterTableView DataKeyNames="Id" CommandItemDisplay="Top">
      <Columns>
         <telerik:GridButtonColumn .../>
      </Columns>
      <EditFormSettings ColumnNumber="1" EditFormType="Template">
         <FormTemplate>
            <asp:ListBox .../>                       
         </FormTemplate>
      </EditFormSettings>               
   </MasterTableView>
</telerik:RadGrid>

Updated:

protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
{
   if (e.Item is GridEditFormItem && e.Item.IsInEditMode)
   {
      var item = e.Item as GridEditFormItem;    

      var listBox1 = item.FindControl("ListBox1") as ListBox;  

      // Fills listbox with data
      listBox1.DataSource = listboxdata;
      listBox1.DataBind();
   }
}