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ListView.Sorting Event

Occurs when a sort operation is requested, but before the ListView control handles the sort operation.

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

public event EventHandler<ListViewSortEventArgs> Sorting
<asp:ListView OnSorting="EventHandler" />

The Sorting event is raised when a Sort button is clicked or the Sort method is called, but before the ListView control handles the sort operation. (A Sort button is a button control whose CommandName property is set to "Sort".) This enables you to perform a custom routine whenever this event occurs, such as customizing the sort expression.

A ListViewSortEventArgs object is passed to the event handler, which enables you to determine the sort expression for the column. It also lets you indicate that the sort operation should be canceled. To cancel the sort operation, set the Cancel property of the ListViewSortEventArgs object to true.

For more information about how to handle events, see Consuming Events.

The following example shows how create an event handler for the Sorting event.

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

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
  void ContactsListView_Sorting(Object sender, ListViewSortEventArgs e)
  {
    // Check the sort direction to set the image URL accordingly.
    string imgUrl;
    if (e.SortDirection == SortDirection.Ascending)
      imgUrl = "~/images/ascending.gif";
    else
      imgUrl = "~/images/descending.gif";

    // Check which field is being sorted
    // to set the visibility of the image controls.
    Image sortImage1 = (Image) ContactsListView.FindControl("SortImage1");
    Image sortImage2 = (Image)ContactsListView.FindControl("SortImage2");
    Image sortImage3 = (Image)ContactsListView.FindControl("SortImage3");
    switch (e.SortExpression)
    {
      case "FirstName":
        sortImage1.Visible = true;
        sortImage1.ImageUrl = imgUrl;
        sortImage2.Visible = false;
        sortImage3.Visible = false;
        break;
      case "LastName":
        sortImage1.Visible = false;
        sortImage2.Visible = true;
        sortImage2.ImageUrl = imgUrl;
        sortImage3.Visible = false;
        break;
      case "EmailAddress":
        sortImage1.Visible = false;
        sortImage2.Visible = false;
        sortImage3.Visible = true;
        sortImage3.ImageUrl = imgUrl;
        break;
    }
  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>ListView Sorting Example</title>
    <style type="text/css">
      body  { font: 10pt Trebuchet MS, Arial, Tahoma; }
      td { border: 1px solid #E6E6FA; }
      .header {	background: #B0C4DE; }
      .alternatingItem { background: #edf5fd; }
    </style>
  </head>
  <body>
    <form id="form1" runat="server">

      <h3>ListView Sorting Example</h3>

      <asp:ListView ID="ContactsListView" 
        DataSourceID="ContactsDataSource" 
        OnSorting="ContactsListView_Sorting"
        runat="server">
        <LayoutTemplate>
          <table width="640px" runat="server" id="tblContacts">
            <tr class="header" align="center" runat="server">
              <td>
                <asp:LinkButton runat="server" ID="SortByFirstNameButton"
                  CommandName="Sort" Text="First Name" 
                  CommandArgument="FirstName"/>
                <asp:Image runat="server" ID="SortImage1" 
                  ImageUrl="~/images/ascending.gif" Visible="false" />
              </td>
              <td>
                <asp:LinkButton runat="server" ID="SortByLastNameButton"
                  CommandName="Sort" Text="Last Name"
                  CommandArgument="LastName" />
                <asp:Image runat="server" ID="SortImage2" 
                  ImageUrl="~/images/ascending.gif" Visible="false" />
              </td>
              <td>
                <asp:LinkButton runat="server" ID="SortByEmailButton"
                  CommandName="Sort" Text="E-mail Address" 
                  CommandArgument="EmailAddress" />
                <asp:Image runat="server" ID="SortImage3" 
                  ImageUrl="~/images/ascending.gif" Visible="false" />
              </td>
            </tr>
            <tr runat="server" id="itemPlaceholder" />
          </table>
          <asp:DataPager runat="server" ID="PeopleDataPager" PageSize="12">
            <Fields>
              <asp:NextPreviousPagerField 
                ShowFirstPageButton="true" ShowLastPageButton="true"
                FirstPageText="|&lt;&lt; " LastPageText=" &gt;&gt;|"
                NextPageText=" &gt; " PreviousPageText=" &lt; " />
            </Fields>
          </asp:DataPager>
        </LayoutTemplate>
        <ItemTemplate>
          <tr runat="server">
            <td>
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("FirstName") %>' />
            </td>
            <td>
              <asp:Label ID="LastNameLabel" runat="server" Text='<%#Eval("LastName") %>' />
            </td>
            <td>
              <asp:Label ID="EmailLabel" runat="server" Text='<%#Eval("EmailAddress") %>' />
            </td>
          </tr>
        </ItemTemplate>
        <AlternatingItemTemplate>
          <tr class="alternatingItem" runat="server">
            <td>
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("FirstName") %>' />
            </td>
            <td>
              <asp:Label ID="LastNameLabel" runat="server" Text='<%#Eval("LastName") %>' />
            </td>
            <td>
              <asp:Label ID="EmailLabel" runat="server" Text='<%#Eval("EmailAddress") %>' />
            </td>
          </tr>
        </AlternatingItemTemplate>
      </asp:ListView>

      <!-- This example uses Microsoft SQL Server and connects    -->
      <!-- to the AdventureWorks sample database. Use an ASP.NET  -->
      <!-- expression to retrieve the connection string value     -->
      <!-- from the Web.config file.                              -->
      <asp:SqlDataSource ID="ContactsDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ContactID], [FirstName], [LastName], [EmailAddress] 
          FROM Person.Contact" >
      </asp:SqlDataSource>

    </form>
  </body>
</html>

.NET Framework

Supported in: 4.5, 4, 3.5

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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