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DataGrid.AllowSorting Property

Gets or sets a value that indicates whether sorting is enabled.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

'Declaration
Public Overridable Property AllowSorting As Boolean
<asp:DataGrid AllowSorting="True|False" />

Property Value

Type: System.Boolean
true if sorting is enabled; otherwise, false. The default value is false.

When sorting is enabled, LinkButton controls are rendered in the heading section of each column where the SortExpression property is set. These LinkButton controls allow you to sort the DataGrid control by the selected column. The only exception is when you use a TemplateColumn column type with the HeaderTemplate property set. In this case, you must provide a Button control in the HeaderTemplate of the column.

The SortCommand event is raised when one of the LinkButton controls is clicked. It is up to you to provide code for the event handler. The typical logic for the handler is to sort the list, and then rebind the data to the DataGrid control.

The following code example demonstrates how to use the AllowSorting property to enable sorting.

<%@ 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 language="VB" runat="server">

    Dim SortExpression As String

    Function CreateDataSource() As ICollection
        Dim dt As New DataTable()
        Dim dr As DataRow
        Dim Rand_Num As New Random()

        dt.Columns.Add(New DataColumn("IntegerValue", GetType(Int32)))
        dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
        dt.Columns.Add(New DataColumn("CurrencyValue", GetType(Double)))

        Dim i As Integer
        For i = 0 To 14
            dr = dt.NewRow()

            dr(0) = i
            dr(1) = "Item " & i.ToString()
            dr(2) = 1.23 * Rand_Num.Next(1, 15)

            dt.Rows.Add(dr)
        Next i

        Dim dv As New DataView(dt)
        dv.Sort = SortExpression
        Return dv
    End Function 'CreateDataSource


    Sub Page_Load(sender As Object, e As EventArgs)

        If Not IsPostBack Then

            If SortExpression = "" Then
                SortExpression = "IntegerValue"
            End If
            ItemsGrid.DataSource = CreateDataSource()
            ItemsGrid.DataBind()
        End If
    End Sub 'Page_Load


    Sub Sort_Grid(sender As Object, e As DataGridSortCommandEventArgs)
        SortExpression = e.SortExpression.ToString()
        ItemsGrid.DataSource = CreateDataSource()
        ItemsGrid.DataBind()
    End Sub 'Sort_Grid

 </script>

 <head runat="server">
    <title>DataGrid Sorting Example</title>
</head>
<body>

    <form id="form1" runat="server">

       <h3>DataGrid Sorting Example</h3>

       <asp:DataGrid id="ItemsGrid" runat="server"
            BorderColor="black"
            BorderWidth="1"
            CellPadding="3"
            AllowSorting="true"
            OnSortCommand="Sort_Grid"
            HeaderStyle-BackColor="#00aaaa"
            AutoGenerateColumns="true"/>

    </form>

 </body>
 </html>
<%@ 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>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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