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ListView.ItemCanceling Evento

Definición

Se produce cuando se solicita una operación de cancelación, pero antes de que el control ListView cancele la operación de inserción o edición.

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

Tipo de evento

Ejemplos

En el ejemplo siguiente se muestra cómo crear un ItemCanceling controlador de eventos.

Importante

Este ejemplo contiene cuadros de texto que aceptan la entrada del usuario, que es una amenaza de seguridad potencial. De forma predeterminada, ASP.NET Web Pages valida que los datos proporcionados por el usuario no incluyen elementos HTML ni de script. Para más información, consulte Información general sobre los ataques mediante scripts.

<%@ 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 Page_Load()
  {
    Message.Text = String.Empty;
  }

  // <Snippet2>
  protected void ContactsListView_ItemCanceling(object sender, ListViewCancelEventArgs e)
  {
    //Check the operation that raised the event
    if (e.CancelMode == ListViewCancelMode.CancelingEdit)
    {
      // The update operation was canceled. Display the 
      // primary key of the item.
      Message.Text = "Update for the ContactID " + 
        ContactsListView.DataKeys[e.ItemIndex].Value.ToString()  + " canceled.";
    }
    else
    {
      Message.Text = "Insert operation canceled."; 
    }
  }
  // </Snippet2>

  protected void ContactsListView_PagePropertiesChanging(object sender, 
    PagePropertiesChangingEventArgs e)
  {
    // Clears the edit index selection when paging.
    ContactsListView.EditIndex = -1;
  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>ListView ItemCanceling Example</title>
  </head>
  <body>
    <form id="form1" runat="server">
        
      <h3>ListView ItemCanceling Example</h3>
      
      <asp:Label ID="Message"
        ForeColor="Red"          
        runat="server"/>
      <br/>
                 
      <asp:ListView ID="ContactsListView" 
        DataSourceID="ContactsDataSource" 
        DataKeyNames="ContactID"
        ConvertEmptyStringToNull="true"
        InsertItemPosition="LastItem"
        runat="server" 
        OnItemCanceling="ContactsListView_ItemCanceling" 
        OnPagePropertiesChanging="ContactsListView_PagePropertiesChanging" >
        <LayoutTemplate>
          <table cellpadding="2" width="680px" border="1" runat="server" id="tblContacts">
            <tr runat="server">
              <th runat="server">&nbsp;</th>
              <th runat="server">ID</th>
              <th runat="server">First Name</th>
              <th runat="server">Last Name</th>
              <th runat="server">Email Address</th>
            </tr>
            <tr runat="server" id="itemPlaceholder" />
          </table>
          <asp:DataPager runat="server" ID="ContactsDataPager" 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 valign="top">
              <asp:LinkButton ID="EditButton" runat="server" Text="Edit" CommandName="Edit" /><br />
            </td>
            <td valign="top">
              <asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
            </td>
            <td valign="top">
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("FirstName") %>' />
            </td>
            <td valign="top">
              <asp:Label ID="LastNameLabel" runat="server" Text='<%#Eval("LastName") %>' />
            </td>
            <td valign="top">
              <asp:Label ID="EmailAddressLabel" runat="server" Text='<%#Eval("EmailAddress") %>' />
              &nbsp;
            </td>
          </tr>
        </ItemTemplate>
        <EditItemTemplate>
          <tr style="background-color: #ADD8E6">
            <td valign="top">
              <asp:LinkButton ID="UpdateButton" runat="server" CommandName="Update" Text="Update" /><br />
              <asp:LinkButton ID="CancelEditButton" runat="server" CommandName="Cancel" Text="Cancel" />
            </td>
            <td>
              <asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
            </td>
            <td>
              <asp:TextBox ID="FirstNameTextBox" runat="server" 
                Text='<%#Bind("FirstName") %>' MaxLength="50" /><br />
            </td>
            <td>
              <asp:TextBox ID="LastNameTextBox" runat="server" 
                Text='<%#Bind("LastName") %>' MaxLength="50" /><br />
            </td>
            <td>
              <asp:TextBox ID="EmailAddressTextBox" runat="server" 
                Text='<%#Bind("EmailAddress") %>' MaxLength="50" /><br />
            </td>
          </tr>
        </EditItemTemplate>
        <InsertItemTemplate>
          <tr style="background-color:#90EE90">
            <td colspan="2">
              <asp:LinkButton ID="InsertButton" runat="server" CommandName="Insert" Text="Insert" /><br />
              <asp:LinkButton ID="CancelInsertButton" runat="server" CommandName="Cancel" Text="Cancel" />
            </td>              
            <td>
              <asp:TextBox ID="FirstNameITextBox" runat="server" 
                Text='<%#Bind("FirstName") %>' MaxLength="50" />
            </td>
            <td>
              <asp:TextBox ID="LastNameITextBox" runat="server" 
                Text='<%#Bind("LastName") %>' MaxLength="50" />
            </td>
            <td>
              <asp:TextBox ID="EmailAddressITextBox" runat="server" 
                Text='<%#Bind("EmailAddress") %>' MaxLength="50" />
           </td>
          </tr>
        </InsertItemTemplate>
      </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"
        InsertCommand="INSERT INTO Person.Contact
                         ([FirstName], [LastName], [EmailAddress], [PasswordHash], [PasswordSalt]) 
                         Values(@FirstName, @LastName, @EmailAddress, '', '')"
        UpdateCommand="UPDATE Person.Contact
                         SET FirstName = @FirstName, LastName = @LastName,
                         EmailAddress = @EmailAddress
                         WHERE ContactID = @ContactID">
      </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">

  Sub Page_Load()
    Message.Text = String.Empty
  End Sub

  ' <Snippet2>
  Protected Sub ContactsListView_ItemCanceling(ByVal sender As Object, _
                                               ByVal e As ListViewCancelEventArgs)
    'Check the operation that raised the event
    If (e.CancelMode = ListViewCancelMode.CancelingEdit) Then
      ' The update operation was canceled. Display the 
      ' primary key of the item.
      Message.Text = "Update for the ContactID " & _
        ContactsListView.DataKeys(e.ItemIndex).Value.ToString() & " canceled."
    Else
      Message.Text = "Insert operation canceled."
    End If

  End Sub
  ' </Snippet2>
  
  Protected Sub ContactsListView_PagePropertiesChanging(ByVal sender As Object, _
                                               ByVal e As PagePropertiesChangingEventArgs)
    ' Clears the edit index selection when paging.
    ContactsListView.EditIndex = -1
  End Sub
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>ListView ItemCanceling Example</title>
  </head>
  <body>
    <form id="form1" runat="server">
        
      <h3>ListView ItemCanceling Example</h3>
      
      <asp:Label ID="Message"
        ForeColor="Red"          
        runat="server"/>
      <br/>
                 
      <asp:ListView ID="ContactsListView" 
        DataSourceID="ContactsDataSource" 
        DataKeyNames="ContactID"
        ConvertEmptyStringToNull="true"
        InsertItemPosition="LastItem"
        runat="server" 
        OnItemCanceling="ContactsListView_ItemCanceling" 
        OnPagePropertiesChanging="ContactsListView_PagePropertiesChanging" >
        <LayoutTemplate>
          <table cellpadding="2" width="680px" border="1" runat="server" id="tblContacts">
            <tr runat="server">
              <th runat="server">&nbsp;</th>
              <th runat="server">ID</th>
              <th runat="server">First Name</th>
              <th runat="server">Last Name</th>
              <th runat="server">Email Address</th>
            </tr>
            <tr runat="server" id="itemPlaceholder" />
          </table>
          <asp:DataPager runat="server" ID="ContactsDataPager" 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 valign="top">
              <asp:LinkButton ID="EditButton" runat="server" Text="Edit" CommandName="Edit" /><br />
            </td>
            <td valign="top">
              <asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
            </td>
            <td valign="top">
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("FirstName") %>' />
            </td>
            <td valign="top">
              <asp:Label ID="LastNameLabel" runat="server" Text='<%#Eval("LastName") %>' />
            </td>
            <td valign="top">
              <asp:Label ID="EmailAddressLabel" runat="server" Text='<%#Eval("EmailAddress") %>' />
              &nbsp;
            </td>
          </tr>
        </ItemTemplate>
        <EditItemTemplate>
          <tr style="background-color: #ADD8E6">
            <td valign="top">
              <asp:LinkButton ID="UpdateButton" runat="server" CommandName="Update" Text="Update" /><br />
              <asp:LinkButton ID="CancelEditButton" runat="server" CommandName="Cancel" Text="Cancel" />
            </td>
            <td>
              <asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
            </td>
            <td>
              <asp:TextBox ID="FirstNameTextBox" runat="server" 
                Text='<%#Bind("FirstName") %>' MaxLength="50" /><br />
            </td>
            <td>
              <asp:TextBox ID="LastNameTextBox" runat="server" 
                Text='<%#Bind("LastName") %>' MaxLength="50" /><br />
            </td>
            <td>
              <asp:TextBox ID="EmailAddressTextBox" runat="server" 
                Text='<%#Bind("EmailAddress") %>' MaxLength="50" /><br />
            </td>
          </tr>
        </EditItemTemplate>
        <InsertItemTemplate>
          <tr style="background-color:#90EE90">
            <td colspan="2">
              <asp:LinkButton ID="InsertButton" runat="server" CommandName="Insert" Text="Insert" /><br />
              <asp:LinkButton ID="CancelInsertButton" runat="server" CommandName="Cancel" Text="Cancel" />
            </td>              
            <td>
              <asp:TextBox ID="FirstNameITextBox" runat="server" 
                Text='<%#Bind("FirstName") %>' MaxLength="50" />
            </td>
            <td>
              <asp:TextBox ID="LastNameITextBox" runat="server" 
                Text='<%#Bind("LastName") %>' MaxLength="50" />
            </td>
            <td>
              <asp:TextBox ID="EmailAddressITextBox" runat="server" 
                Text='<%#Bind("EmailAddress") %>' MaxLength="50" />
           </td>
          </tr>
        </InsertItemTemplate>
      </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"
        InsertCommand="INSERT INTO Person.Contact
                         ([FirstName], [LastName], [EmailAddress], [PasswordHash], [PasswordSalt]) 
                         Values(@FirstName, @LastName, @EmailAddress, '', '')"
        UpdateCommand="UPDATE Person.Contact
                         SET FirstName = @FirstName, LastName = @LastName,
                         EmailAddress = @EmailAddress
                         WHERE ContactID = @ContactID">
      </asp:SqlDataSource>
      
    </form>
  </body>
</html>

Comentarios

El ListView control genera el ItemCanceling evento cuando se hace clic en un botón Cancelar de la InsertItemTemplate plantilla o EditItemTemplate , pero antes de que el ListView control cancele la operación de inserción o edición. (Un botón Cancelar es un control de botón cuya CommandName propiedad está establecida en "Cancelar"). Esto le permite realizar una rutina personalizada cada vez que se produzca este evento, como detener la operación de cancelación si colocaría el elemento en un estado no deseado.

Un ListViewCancelEventArgs objeto se pasa al controlador de eventos, lo que permite determinar el índice del elemento. También le permite indicar que se debe detener la operación de cancelación. Para detener la operación, establezca la Cancel propiedad del ListViewCancelEventArgs objeto en true.

Para obtener más información acerca de cómo controlar eventos, vea controlar y provocar eventos.

Se aplica a

Consulte también