RadControls for ASP.NET AJAX RadGrid loses its current selection when the data is
sorted, a new group or filter is added, or when the current page changes. If
you want the selection to persist across these events, you can do the
following:
Add an ItemCommand event handler to the grid.
When a "Select" command occurs, store the key values for the
selected row in a Session variable.
When a "Deselect" command occurs, remove the key values from
the Session variable.
Add a PreRender event handler to the grid.
In the pre-render event of the grid, traverse the rows of the
grid and compare their key values to the values saved in the
Session variable. Whenever you find a match,
select the row.
 Caution |
|---|
This example only
works if you have not enabled client-side selection (that is, you are
selecting rows using Command buttons).
|
CopyASPX
<telerik:RadGrid ID="RadGrid1" runat="server" DataSourceID="SqlDataSource1" Width="97%"
AllowPaging="True" PageSize="15" AllowSorting="True" AllowMultiRowSelection="True"
ShowGroupPanel="True" AllowFilteringByColumn="true" OnItemCommand="RadGrid1_ItemCommand"
OnPreRender="RadGrid1_PreRender">
<PagerStyle Mode="NextPrevAndNumeric" />
<MasterTableView Width="100%" DataKeyNames="CustomerID" AllowFilteringByColumn="true">
<Columns>
<telerik:GridButtonColumn UniqueName="SelectColumn" CommandName="Select" Text="Select" />
<telerik:GridButtonColumn UniqueName="DeselectColumn" CommandName="Deselect" Text="Deselect" />
</Columns>
</MasterTableView>
<ClientSettings AllowDragToGroup="True" />
</telerik:RadGrid>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
SelectCommand="SELECT TOP 10 [CustomerID], [ContactName], [ContactTitle], [Address] FROM [Customers]">
</asp:SqlDataSource>
In the code-behind, the ItemCommand handler saves the key values, and the
PreRender handler uses them to restore the selection:
CopyC#
protected void RadGrid1_ItemCommand(object source, GridCommandEventArgs e)
{
ArrayList selectedItems;
if (Session["selectedItems"] == null)
{
selectedItems = new ArrayList();
}
else
{
selectedItems = (ArrayList)Session["selectedItems"];
}
if (e.CommandName == RadGrid.SelectCommandName && e.Item is GridDataItem)
{
GridDataItem dataItem = (GridDataItem)e.Item;
string customerID = dataItem.OwnerTableView.DataKeyValues[dataItem.ItemIndex]["CustomerID"].ToString();
selectedItems.Add(customerID);
Session["selectedItems"] = selectedItems;
}
if (e.CommandName == RadGrid.DeselectCommandName && e.Item is GridDataItem)
{
GridDataItem dataItem = (GridDataItem)e.Item;
string customerID = dataItem.OwnerTableView.DataKeyValues[dataItem.ItemIndex]["CustomerID"].ToString();
selectedItems.Remove(customerID);
Session["selectedItems"] = selectedItems;
}
}
protected void RadGrid1_PreRender(object sender, EventArgs e)
{
if (Session["selectedItems"] != null)
{
ArrayList selectedItems = (ArrayList)Session["selectedItems"];
Int16 stackIndex;
for (stackIndex = 0; stackIndex <= selectedItems.Count - 1; stackIndex++)
{
string curItem = selectedItems[stackIndex].ToString();
foreach (GridItem item in RadGrid1.MasterTableView.Items)
{
if (item is GridDataItem)
{
GridDataItem dataItem = (GridDataItem)item;
if (curItem.Equals(dataItem.OwnerTableView.DataKeyValues[dataItem.ItemIndex]["CustomerID"].ToString()))
{
dataItem.Selected = true;
break;
}
}
}
}
}
}CopyVB.NET
Protected Sub RadGrid1_ItemCommand(ByVal source As Object, ByVal e As GridCommandEventArgs) Handles RadGrid1.ItemCommand
Dim selectedItems As ArrayList
If Session("selectedItems") Is Nothing Then
selectedItems = New ArrayList
Else
selectedItems = CType(Session("selectedItems"), ArrayList)
End If
If e.CommandName = RadGrid.SelectCommandName AndAlso TypeOf e.Item Is GridDataItem Then
Dim dataItem As GridDataItem = CType(e.Item, GridDataItem)
Dim customerID As String = dataItem.OwnerTableView.DataKeyValues(dataItem.ItemIndex)("CustomerID").ToString
selectedItems.Add(customerID)
Session("selectedItems") = selectedItems
End If
If e.CommandName = RadGrid.DeselectCommandName AndAlso TypeOf e.Item Is GridDataItem Then
Dim dataItem As GridDataItem = CType(e.Item, GridDataItem)
Dim customerID As String = dataItem.OwnerTableView.DataKeyValues(dataItem.ItemIndex)("CustomerID").ToString
selectedItems.Remove(customerID)
Session("selectedItems") = selectedItems
End If
End Sub
Protected Sub RadGrid1_PreRender(ByVal sender As Object, ByVal e As EventArgs) Handles RadGrid1.PreRender
If Not (Session("selectedItems") Is Nothing) Then
Dim selectedItems As ArrayList = CType(Session("selectedItems"), ArrayList)
Dim stackIndex As Int16
For stackIndex = 0 To selectedItems.Count - 1
Dim curItem As String = selectedItems(stackIndex).ToString
For Each item As GridItem In RadGrid1.MasterTableView.Items
If TypeOf item Is GridDataItem Then
Dim dataItem As GridDataItem = CType(item, GridDataItem)
If curItem.Equals(dataItem.OwnerTableView.DataKeyValues(dataItem.ItemIndex)("CustomerID").ToString()) Then
dataItem.Selected = True
End If
End If
Next
Next
End If
End Sub
See Also