DataGridSortCommandEventHandler Delegate
Represents the method that handles the SortCommand event of the DataGrid control.
Assembly: System.Web (in System.Web.dll)
Public Delegate Sub DataGridSortCommandEventHandler ( source As Object, e As DataGridSortCommandEventArgs )
Parameters
- source
-
Type:
System.Object
The source of the event.
- e
-
Type:
System.Web.UI.WebControls.DataGridSortCommandEventArgs
A DataGridSortCommandEventArgs that contains the event data.
When sorting is enabled by setting the AllowSorting property of the DataGrid control to true, LinkButton controls are rendered in the header of each column. These links allow you to sort the DataGrid control by the selected column. The SortCommand event is raised when a LinkButton control is clicked.
When you create a DataGridSortCommandEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see NIB: Events and Delegates.
The following code example demonstrates how to specify and code a handler for the SortCommand event to sort a DataGrid control.
<%@ Page Language="VB" %> <%@ Import Namespace="System.Data" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> Function CreateDataSource() As ICollection ' Create a Random object to mix up the order ' of items in the sample data. Dim randNum As Random = New Random() ' Create sample data for the DataGrid control. Dim dt As DataTable = New DataTable() ' Define the columns of the table. dt.Columns.Add( _ New DataColumn("IntegerValue", GetType(Int32))) dt.Columns.Add( _ New DataColumn("StringValue", GetType(String))) dt.Columns.Add( _ New DataColumn("CurrencyValue", GetType(Double))) ' Populate the table with sample values. Dim i As Integer For i = 0 To 8 Dim dr As DataRow = dt.NewRow() dr(0) = i dr(1) = "Item " & randNum.Next(1, 15).ToString() dr(2) = 1.23 * randNum.Next(1, 15) dt.Rows.Add(dr) Next ' Persist the data source between posts to ' the server, in the session state. Session("Source") = dt Dim dv As DataView = New DataView(dt) Return dv End Function Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) ' Load sample data when the page is first loaded. If Not IsPostBack Then ItemsGrid.DataSource = CreateDataSource() ItemsGrid.DataBind() End If End Sub Sub Sort_Grid(ByVal sender As Object, _ ByVal e As DataGridSortCommandEventArgs) ' Retrieve the data source from session state. Dim dt As DataTable = _ CType(Session("Source"), DataTable) ' Create a DataView from the DataTable. Dim dv As DataView = New DataView(dt) ' The DataView provides an easy way to ' sort. Simply set the Sort property with ' the name of the field to sort by. dv.Sort = e.SortExpression ' Rebind the data source and specify that ' it should be sorted by the field specified ' in the SortExpression property. ItemsGrid.DataSource = dv ItemsGrid.DataBind() End Sub Sub Check_Change(ByVal sender As Object, _ ByVal e As EventArgs) ' Allow or prevent sorting depending ' on the user's selection. ItemsGrid.AllowSorting = _ AllowSortingCheckBox.Checked ' After changing the property, rebind ' the data to refresh the DataGrid control. ' Retrieve data source from session state. Dim dt As DataTable = _ CType(Session("Source"), DataTable) ' Create a DataView from the DataTable. Dim dv As DataView = New DataView(dt) ' Rebind the data source. ItemsGrid.DataSource = dv ItemsGrid.DataBind() End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server"> <title> ExtractTemplateRows Example </title> </head> <body> <form id="form1" runat="server"> <div> <h3>DataGrid AllowSorting Example</h3> <p>Select whether to allow sorting in the DataGrid control.<br /> <asp:CheckBox id="AllowSortingCheckBox" Text="Allow sorting" AutoPostBack="True" Checked="True" OnCheckedChanged="Check_Change" runat="server"/></p> <hr /> <b>Product List</b> <asp:DataGrid id="ItemsGrid" BorderColor="black" BorderWidth="1" CellPadding="3" OnSortCommand="Sort_Grid" UseAccessibleHeader="true" AutoGenerateColumns="False" AllowSorting="True" runat="server"> <HeaderStyle BackColor="#00aaaa" /> <Columns> <asp:BoundColumn DataField="IntegerValue" SortExpression="IntegerValue" HeaderText="Item"/> <asp:BoundColumn DataField="StringValue" SortExpression="StringValue" HeaderText="Description"/> <asp:BoundColumn DataField="CurrencyValue" HeaderText="Price" SortExpression="CurrencyValue" DataFormatString="{0:c}"> <ItemStyle HorizontalAlign="Right"> </ItemStyle> </asp:BoundColumn> </Columns> </asp:DataGrid> </div> </form> </body> </html>
<%@ Page Language="VB" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <script runat="server"> Function CreateDataSource() As ICollection ' Create a Random object to mix up the order of items in the sample data. Dim Rand_Num As Random = New Random() ' Create sample data for the DataGrid control. Dim dt As DataTable = New DataTable() Dim dr As DataRow ' Define the columns of the table. dt.Columns.Add(new DataColumn("IntegerValue", GetType(Int32))) dt.Columns.Add(new DataColumn("StringValue", GetType(String))) dt.Columns.Add(new DataColumn("CurrencyValue", GetType(Double))) ' Populate the table with sample values. Dim i As Integer For i = 0 To 8 dr = dt.NewRow() dr(0) = i dr(1) = "Item " & Rand_Num.Next(1, 15).ToString() dr(2) = 1.23 * Rand_Num.Next(1, 15) dt.Rows.Add(dr) Next i ' To persist the data source between posts to the server, store it ' in session state. Session("Source") = dt Dim dv As DataView = New DataView(dt) Return dv End Function Sub Page_Load(sender As Object, e As EventArgs) ' Load sample data only once, when the page is first loaded. If Not IsPostBack Then ItemsGrid.DataSource = CreateDataSource() ItemsGrid.DataBind() End If ' Manually register the event-handling method for the PageIndexChanged ' event of the DataGrid control. AddHandler ItemsGrid.SortCommand, AddressOf Sort_Grid End Sub Sub Sort_Grid(sender As Object, e As DataGridSortCommandEventArgs) ' Retrieve the data source from session state. Dim dt As DataTable = CType(Session("Source"), DataTable) ' Create a DataView from the DataTable. Dim dv As DataView = New DataView(dt) ' The DataView provides an easy way to sort. Simply set the Sort property with ' the name of the field to sort by. dv.Sort = e.SortExpression ' Re-bind the data source and specify that it should be sorted ' by the field specified in the SortExpression property. ItemsGrid.DataSource = dv ItemsGrid.DataBind() End Sub Sub Check_Change(sender As Object, e As EventArgs) ' Allow or prevent sorting depending on the user's selection. If AllowSortingCheckBox.Checked Then ItemsGrid.AllowSorting = True Else ItemsGrid.AllowSorting = False End If ' After changing the property, re-bind the data to ' refresh the DataGrid control. ' Retrieve the data source from session state. Dim dt As DataTable = CType(Session("Source"), DataTable) ' Create a DataView from the DataTable. Dim dv As DataView = New DataView(dt) ' Re-bind the data source. ItemsGrid.DataSource = dv ItemsGrid.DataBind() End Sub </script> <head runat="server"> <title>DataGrid SortCommand Example</title> </head> <body> <form id="form1" runat="server"> <h3>DataGrid SortCommand Example</h3> Select whether to allow sorting in the DataGrid control. <br /><br /> <b>Product List</b> <asp:DataGrid id="ItemsGrid" BorderColor="black" BorderWidth="1" CellPadding="3" AutoGenerateColumns="False" AllowSorting="True" runat="server"> <HeaderStyle BackColor="#00aaaa"> </HeaderStyle> <Columns> <asp:BoundColumn DataField="IntegerValue" SortExpression="IntegerValue" HeaderText="Item"/> <asp:BoundColumn DataField="StringValue" SortExpression="StringValue" HeaderText="Description"/> <asp:BoundColumn DataField="CurrencyValue" HeaderText="Price" SortExpression="CurrencyValue" DataFormatString="{0:c}"> <ItemStyle HorizontalAlign="Right"> </ItemStyle> </asp:BoundColumn> </Columns> </asp:DataGrid> <hr /> <asp:CheckBox id="AllowSortingCheckBox" Text="Allow sorting" AutoPostBack="True" Checked="True" OnCheckedChanged="Check_Change" runat="server"/> </form> </body> </html>
Available since 1.1