RadGrid for ASP.NET AJAX

Protected Sub RadGrid1_ItemCreated(ByVal sender As Object, ByVal e As GridItemEventArgs) Handles RadGrid1.ItemCreated
    'if a grid item is in edit mode, wire the ItemsRequested event of the customersCombo to filter the items in it based on the selection in the freight combo
    If TypeOf e.Item Is GridEditableItem AndAlso e.Item.IsInEditMode Then
        Dim freightCombo As RadComboBox = TryCast(TryCast(e.Item, GridEditableItem)("Freight").Controls(0), RadComboBox)

        If Page.IsCallback Then
            Dim customersCombo As RadComboBox = TryCast(TryCast(e.Item, GridEditableItem)("CustomerName").Controls(0), RadComboBox)
            AddHandler customersCombo.ItemsRequested, AddressOf customersCombo_ItemsRequested
        End If
    End If
End Sub

Protected Sub RadGrid1_ItemDataBound(ByVal sender As Object, ByVal e As GridItemEventArgs) Handles RadGrid1.ItemDataBound
    If TypeOf e.Item Is GridEditableItem AndAlso e.Item.IsInEditMode AndAlso (Not e.Item.OwnerTableView.IsItemInserted) Then
        'wire the OnClientSelectedIndexChanged event of the first LOD combo editor to initiate callback on item selection
        Dim freightCombo As RadComboBox = TryCast(TryCast(e.Item, GridEditableItem)("Freight").Controls(0), RadComboBox)
        freightCombo.OnClientSelectedIndexChanged = "freightComboClientSelectedIndexChangedHandler"

        'set the selected value for the Employees combobox to match the value in the edited cell
        Dim employeesCombo As RadComboBox = TryCast(TryCast(e.Item, GridEditableItem).FindControl("RadComboBox1"), RadComboBox)
        employeesCombo.Items(0).Text = DataBinder.Eval(e.Item.DataItem, "LastName").ToString()

        'set the selection in the treeview inside the combobox to match the value in the edited cell
        Dim employeesTreeView As RadTreeView = TryCast(employeesCombo.Items(0).FindControl("RadTreeView1"), RadTreeView)
        employeesTreeView.FindNodeByText(DataBinder.Eval(e.Item.DataItem, "LastName").ToString()).Selected = True
        'Expand all nodes to scroll the selected into view. Have in mind that load-on-demand is recommended with very large number of nodes in the treeview 
        employeesTreeView.ExpandAllNodes()

        'register script block which holds the client id of the employeesComboBox. Will be used to reference the client object of the combobox in the RadTreeView's OnClientNodeClicking event handler


        RadScriptManager.RegisterClientScriptBlock(Me.Page, GetType(Page), "employeesComboScript", "<script type='text/javascript'>window['comboId'] = '" + e.Item.FindControl("RadComboBox1").ClientID + "';</script>", False)
    ElseIf TypeOf e.Item Is GridDataInsertItem Then
        'wire the OnClientSelectedIndexChanged event of the first LOD combo editor to initiate callback on item selection
        Dim freightCombo As RadComboBox = TryCast(TryCast(e.Item, GridDataInsertItem)("Freight").Controls(0), RadComboBox)
        freightCombo.OnClientSelectedIndexChanged = "freightComboClientSelectedIndexChangedHandler"

        'register script block which holds the client id of the employeesComboBox. Will be used to reference the client object of the combobox in the RadTreeView's OnClientNodeClicking event handler
        RadScriptManager.RegisterClientScriptBlock(Me.Page, GetType(Page), "employeesComboScript", "<script type='text/javascript'>window['comboId'] = '" + e.Item.FindControl("RadComboBox1").ClientID + "';</script>", False)
    End If
End Sub

Private Sub customersCombo_ItemsRequested(ByVal sender As Object, ByVal e As RadComboBoxItemsRequestedEventArgs)
    LoadFilteredCustomersManually(e.Text, TryCast(sender, RadComboBox))
End Sub

Protected Sub LoadFilteredCustomersManually(ByVal freight As String, ByVal customersCombo As RadComboBox)
    'if the orderID value cannot be parsed as integer(i.e. auto LOD is triggered), exit the handler
    Try
        Dim fid As Double = System.[Double].Parse(freight)
    Catch
        Return
    End Try

    Dim connection As New SqlConnection(ConfigurationManager.ConnectionStrings("NorthwindConnectionString").ConnectionString)
    connection.Open()

    'select customer name based on the orderID
    Dim comm As New SqlCommand("SELECT CustomerID FROM [Orders] WHERE Freight=@Freight", connection)
    comm.Parameters.AddWithValue("@Freight", freight)

    Dim cid As String = comm.ExecuteScalar().ToString()

    comm = New SqlCommand("SELECT CustomerID, ContactName from [Customers] WHERE CustomerID = '" + cid + "'", connection)
    Dim adapter As New SqlDataAdapter(comm)

    Dim dt As New DataTable()
    adapter.Fill(dt)

    'populate the customers combo with the new set of items
    customersCombo.Items.Clear()

    For Each row As DataRow In dt.Rows
        customersCombo.Items.Add(New RadComboBoxItem(row("ContactName").ToString(), row("CustomerID").ToString()))
    Next
    connection.Close()
End Sub

Protected Sub RadGrid1_UpdateCommand(ByVal sender As Object, ByVal e As GridCommandEventArgs) Handles RadGrid1.UpdateCommand
    Dim empId As String = TryCast(TryCast(TryCast(e.Item, GridEditableItem).FindControl("RadComboBox1"), RadComboBox).Items(0).FindControl("RadTreeView1"), RadTreeView).SelectedNode.Value

    'if the EmployeeID value is empty, cancel the update operation
    If empId = String.Empty Then
        e.Canceled = True
        SetMessage("Order cannot be updated. You must select an employee from the provided list")
    Else
        OrdersDataSource.UpdateParameters("EmployeeID").DefaultValue = empId
    End If
End Sub

Protected Sub RadGrid1_InsertCommand(ByVal sender As Object, ByVal e As GridCommandEventArgs) Handles RadGrid1.InsertCommand
    'if the EmployeeID value is empty, cancel the insert operation
    If TryCast(TryCast(TryCast(e.Item, GridEditableItem).FindControl("RadComboBox1"), RadComboBox).Items(0).FindControl("RadTreeView1"), RadTreeView).SelectedNode Is Nothing Then
        e.Canceled = True
        SetMessage("Order cannot be inserted. You must select an employee from the provided list")
    Else
        Dim empId As String = TryCast(TryCast(TryCast(e.Item, GridEditableItem).FindControl("RadComboBox1"), RadComboBox).Items(0).FindControl("RadTreeView1"), RadTreeView).SelectedNode.Value
        OrdersDataSource.InsertParameters("EmployeeID").DefaultValue = empId
    End If
End Sub

Protected Sub RadGrid1_ItemCommand(ByVal sender As Object, ByVal e As GridCommandEventArgs) Handles RadGrid1.ItemCommand
    'switch the edit/insert modes to ensure that only one operation will be processed at given time
    If e.CommandName = RadGrid.EditCommandName Then
        e.Item.OwnerTableView.IsItemInserted = False
    ElseIf e.CommandName = RadGrid.InitInsertCommandName Then
        RadGrid1.EditIndexes.Clear()
    End If

End Sub

Public Sub SetMessage(ByVal message As String)
    lblMessage.Text = message
End Sub