DataGridSortCommandEventArgs.SortExpression Property

Reference

Definition

Namespace:: System.Web.UI.WebControls

Assembly:: System.Web.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Gets the expression used to sort the DataGrid control.

public:
 property System::String ^ SortExpression { System::String ^ get(); };

public string SortExpression { get; }

member this.SortExpression : string

Public ReadOnly Property SortExpression As String

Property Value

String

The expression used to sort the DataGrid control.

Examples

The following code example demonstrates how to use the SortExpression property to determine which column the user selected to sort the DataGrid control by.

<%@ Page Language="C#" 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">

<script runat="server">
    ICollection CreateDataSource()
    {
        // Create a Random object to mix up the 
        // order of items in the sample data.
        Random randNum = new Random();

        // Create sample data for the DataGrid control.
        DataTable dt = new DataTable();

        // Define the columns of the table.
        dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
        dt.Columns.Add(new DataColumn("StringValue", typeof(String)));
        dt.Columns.Add(new DataColumn("CurrencyValue", typeof(Double)));

        // Populate the table with sample values.
        for (int i = 0; i <= 8; i++)
        {
            DataRow dr = 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);
        }

        // To persist the data source between posts to the server,
        // store it in session state.  
        Session["Source"] = dt;
        DataView dv = new DataView(dt);
        return dv;
    }

    void Page_Load(Object sender, EventArgs e)
    {
        // Load sample data only once, when the page is first loaded.
        if (!IsPostBack)
        {
            ItemsGrid.DataSource = CreateDataSource();
            ItemsGrid.DataBind();
        }
    }

    void Sort_Grid(Object sender, DataGridSortCommandEventArgs e)
    {
        // Retrieve the data source from session state.
        DataTable dt = (DataTable)Session["Source"];

        // Create a DataView from the DataTable.
        DataView dv = 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();
    }

    void Check_Change(Object sender, EventArgs e)
    {
        // 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 the data source from session state.
        DataTable dt = (DataTable)Session["Source"];

        // Create a DataView from the DataTable.
        DataView dv = new DataView(dt);

        // Rebind the data source.
        ItemsGrid.DataSource = dv;
        ItemsGrid.DataBind();
    }
</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" %>
<%@ 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>

Remarks

Use the SortExpression property to determine which column the user selected to sort the DataGrid control.

Applies to

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