ListView.ItemDeleting Zdarzenie

Definicja

Występuje, gdy zażądano operacji usuwania, ale przed ListView usunięciem elementu przez formant.Occurs when a delete operation is requested, but before the ListView control deletes the item.

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

Typ zdarzenia

EventHandler<ListViewDeleteEventArgs>

Przykłady

Poniższy przykład pokazuje, jak deklaratywnie dodać program obsługi zdarzeń dla ItemDeleting zdarzenia.The following example shows how to declaratively add an event handler for the ItemDeleting 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">
  protected void CategoriesListView_OnItemDeleting(object sender, ListViewDeleteEventArgs e)
  {
    if (SubCategoriesGridView.Rows.Count > 0)
    {
      MessageLabel.Text = "You cannot delete a category that has sub-categories.";
      e.Cancel = true;
    }
  }

  protected void Page_Load()
  {
    MessageLabel.Text = String.Empty;
  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>Subcategories List</title>
  </head>
  <body>
    <form id="form1" runat="server">
      <b>Categories</b>
      <br />
      
      <asp:Label ForeColor="Red" runat="server" ID="MessageLabel" /><br />
      
      <asp:ListView runat="server" 
        ID="CategoriesListView"
        OnItemDeleting="CategoriesListView_OnItemDeleting"
        DataSourceID="CategoriesDataSource" 
        DataKeyNames="ProductCategoryID">
        <LayoutTemplate>
          <table runat="server" id="tblCategories" 
                 cellspacing="0" cellpadding="1" width="440px" border="1">
            <tr id="itemPlaceholder" runat="server"></tr>
          </table>
        </LayoutTemplate>
        <ItemTemplate>
          <tr runat="server">
            <td>
              <asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
            </td>
            <td style="width:40px">
              <asp:LinkButton runat="server" ID="SelectCategoryButton" 
                Text="Select" CommandName="Select" />
            </td>
          </tr>
        </ItemTemplate>
        <SelectedItemTemplate>
          <tr runat="server" style="background-color:#90EE90">
            <td>
              <asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
            </td>
            <td style="width:40px">
              <asp:LinkButton runat="server" ID="SelectCategoryButton" 
                Text="Delete" CommandName="Delete" />
            </td>
          </tr>
        </SelectedItemTemplate>
      </asp:ListView>
      
      <br />
      
      <b>Subcategories</b>
      <asp:GridView runat="server" ID="SubCategoriesGridView" Width="300px"
           DataSourceID="SubCategoriesDataSource" DataKeyNames="ProductSubcategoryID" 
           AutoGenerateColumns="True" />
       
      <!-- 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="CategoriesDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ProductCategoryID], [Name]
                       FROM Production.ProductCategory">
      </asp:SqlDataSource>
      <asp:SqlDataSource ID="SubCategoriesDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ProductSubcategoryID], [Name]
                       FROM Production.ProductSubcategory
                       WHERE ProductCategoryID = @ProductCategoryID
                       ORDER BY [Name]">
          <SelectParameters>
            <asp:ControlParameter Name="ProductCategoryID" DefaultValue="0"
                 ControlID="CategoriesListView" PropertyName="SelectedValue"  />
          </SelectParameters>
      </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">
    Protected Sub CategoriesListView_OnItemDeleting(sender As Object, e As ListViewDeleteEventArgs)
        If SubCategoriesGridView.Rows.Count > 0 Then
            MessageLabel.Text = "You cannot delete a category that has sub-categories."
            e.Cancel = True
        End If
    End Sub

    Protected Sub Page_Load()
        MessageLabel.Text = String.Empty
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>Subcategories List</title>
  </head>
  <body>
    <form id="form1" runat="server">
      <b>Categories</b>
      <br />
      
      <asp:Label ForeColor="Red" runat="server" ID="MessageLabel" /><br />
      
      <asp:ListView runat="server" 
        ID="CategoriesListView"
        OnItemDeleting="CategoriesListView_OnItemDeleting"
        DataSourceID="CategoriesDataSource" 
        DataKeyNames="ProductCategoryID">
        <LayoutTemplate>
          <table runat="server" id="tblCategories" 
                 cellspacing="0" cellpadding="1" width="440px" border="1">
            <tr id="itemPlaceholder" runat="server"></tr>
          </table>
        </LayoutTemplate>
        <ItemTemplate>
          <tr runat="server">
            <td>
              <asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
            </td>
            <td style="width:40px">
              <asp:LinkButton runat="server" ID="SelectCategoryButton" 
                Text="Select" CommandName="Select" />
            </td>
          </tr>
        </ItemTemplate>
        <SelectedItemTemplate>
          <tr runat="server" style="background-color:#90EE90">
            <td>
              <asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
            </td>
            <td style="width:40px">
              <asp:LinkButton runat="server" ID="SelectCategoryButton" 
                Text="Delete" CommandName="Delete" />
            </td>
          </tr>
        </SelectedItemTemplate>
      </asp:ListView>
      
      <br />
      
      <b>Subcategories</b>
      <asp:GridView runat="server" ID="SubCategoriesGridView" Width="300px"
           DataSourceID="SubCategoriesDataSource" DataKeyNames="ProductSubcategoryID" 
           AutoGenerateColumns="True" />
       
      <!-- 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="CategoriesDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ProductCategoryID], [Name]
                       FROM Production.ProductCategory">
      </asp:SqlDataSource>
      <asp:SqlDataSource ID="SubCategoriesDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ProductSubcategoryID], [Name]
                       FROM Production.ProductSubcategory
                       WHERE ProductCategoryID = @ProductCategoryID
                       ORDER BY [Name]">
          <SelectParameters>
            <asp:ControlParameter Name="ProductCategoryID" DefaultValue="0"
                 ControlID="CategoriesListView" PropertyName="SelectedValue"  />
          </SelectParameters>
      </asp:SqlDataSource>
    </form>
  </body>
</html>

Uwagi

ItemDeletingZdarzenie jest zgłaszane, gdy kliknięto przycisk usuwania elementu lub DeleteItem Metoda jest wywoływana, ale przed ListView usunięciem elementu przez formant.The ItemDeleting event is raised when an item's Delete button is clicked or the DeleteItem method is called, but before the ListView control deletes the item. (Przycisk usuwania jest formantem przycisku, którego CommandName Właściwość jest ustawiona na wartość "Usuń"). Dzięki temu można wykonać niestandardową procedurę przy każdym wystąpieniu tego zdarzenia, na przykład anulowanie operacji usuwania.(A Delete button is a button control whose CommandName property is set to "Delete".) This enables you to perform a custom routine whenever this event occurs, such as canceling the delete operation.

ListViewDeleteEventArgsObiekt jest przesyłany do procedury obsługi zdarzeń, co umożliwia określenie indeksu bieżącego elementu.A ListViewDeleteEventArgs object is passed to the event handler, which enables you to determine the index of the current item. Pozwala również wskazać, że operacja usuwania powinna zostać anulowana.It also lets you indicate that the delete operation should be canceled. Aby anulować operację usuwania, ustaw Cancel Właściwość ListViewDeleteEventArgs obiektu na true .To cancel the delete operation, set the Cancel property of the ListViewDeleteEventArgs object to true. Możesz również współpracować z Keys Values kolekcjami i, zanim wartości zostaną przesłane do źródła danych.You can also work with the Keys and Values collections before the values are passed to the data source.

Aby uzyskać więcej informacji o sposobie obsługi zdarzeń, zobacz Obsługa iwywoływanie zdarzeń.For more information about how to handle events, see Handling and Raising Events.

Dotyczy

Zobacz też