ListView.Sorting ListView.Sorting ListView.Sorting ListView.Sorting Event

Definizione

Si verifica quando viene richiesta un'operazione di ordinamento, ma prima che il controllo ListView gestisca l'operazione di ordinamento.Occurs when a sort operation is requested, but before the ListView control handles the sort operation.

public:
 event EventHandler<System::Web::UI::WebControls::ListViewSortEventArgs ^> ^ Sorting;
public event EventHandler<System.Web.UI.WebControls.ListViewSortEventArgs> Sorting;
member this.Sorting : EventHandler<System.Web.UI.WebControls.ListViewSortEventArgs> 
Public Custom Event Sorting As EventHandler(Of ListViewSortEventArgs) 

Esempi

Nell'esempio seguente viene illustrato come creare un gestore eventi per Sorting l'evento.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">
  //<Snippet2>
  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;
    }
  }
  //</Snippet2>
</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="Email 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>
<%@ Page language="VB" %>
    
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    
<script runat="server">
 '<Snippet2>
  Sub ContactsListView_Sorting(ByVal sender As Object, ByVal e As ListViewSortEventArgs) 
  
    ' Check the sort direction to set the image URL accordingly.
    Dim imgUrl As String
    If e.SortDirection = SortDirection.Ascending Then
      imgUrl = "~/images/ascending.gif"
    Else
      imgUrl = "~/images/descending.gif"
    End If
    
    ' Check which field is being sorted
    ' to set the visibility of the image controls.
    Dim sortImage1 As Image = CType(ContactsListView.FindControl("SortImage1"), Image)
    Dim sortImage2 As Image = CType(ContactsListView.FindControl("SortImage2"), Image)
    Dim sortImage3 As Image = CType(ContactsListView.FindControl("SortImage3"), Image)
    
    Select Case e.SortExpression
      Case "FirstName"
        sortImage1.Visible = True
        sortImage1.ImageUrl = imgUrl
        sortImage2.Visible = False
        sortImage3.Visible = False
      Case "LastName"
        sortImage1.Visible = False
        sortImage2.Visible = True
        sortImage2.ImageUrl = imgUrl
        sortImage3.Visible = False
      Case "EmailAddress"
        sortImage1.Visible = False
        sortImage2.Visible = False
        sortImage3.Visible = True
        sortImage3.ImageUrl = imgUrl
    End Select
    
  End Sub
  '</Snippet2>
</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="Email 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>

Commenti

L' Sorting evento viene generato quando si fa clic su un pulsante di ordinamento Sort o viene chiamato il metodo, ma ListView prima che il controllo gestisca l'operazione di ordinamento.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. Un pulsante di ordinamento è un controllo Button la CommandName cui proprietà è impostata su "Sort". In questo modo è possibile eseguire una routine personalizzata ogni volta che si verifica questo evento, ad esempio personalizzando l'espressione di ordinamento.(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.

Un ListViewSortEventArgs oggetto viene passato al gestore eventi, che consente di determinare l'espressione di ordinamento per la colonna.A ListViewSortEventArgs object is passed to the event handler, which enables you to determine the sort expression for the column. Consente inoltre di indicare che l'operazione di ordinamento deve essere annullata.It also lets you indicate that the sort operation should be canceled. Per annullare l'operazione di ordinamento, impostare Cancel la proprietà ListViewSortEventArgs dell'oggetto su true.To cancel the sort operation, set the Cancel property of the ListViewSortEventArgs object to true.

Per altre informazioni su come gestire gli eventi, vedere la gestione e generazione di eventi.For more information about how to handle events, see Handling and Raising Events.

Si applica a

Vedi anche