GridViewDeleteEventHandler Delegat

Odwołanie

Definicja

Przestrzeń nazw:: System.Web.UI.WebControls

Zestaw:: System.Web.dll

Ważne

Niektóre informacje odnoszą się do produktu w wersji wstępnej, który może zostać znacząco zmodyfikowany przed wydaniem. Firma Microsoft nie udziela żadnych gwarancji, jawnych lub domniemanych, w odniesieniu do informacji podanych w tym miejscu.

Reprezentuje metodę, która obsługuje RowDeleting zdarzenie kontrolki GridView .

public delegate void GridViewDeleteEventHandler(System::Object ^ sender, GridViewDeleteEventArgs ^ e);

public delegate void GridViewDeleteEventHandler(object sender, GridViewDeleteEventArgs e);

type GridViewDeleteEventHandler = delegate of obj * GridViewDeleteEventArgs -> unit

Public Delegate Sub GridViewDeleteEventHandler(sender As Object, e As GridViewDeleteEventArgs)

Parametry

sender: Object

Źródło zdarzenia.

e: GridViewDeleteEventArgs

GridViewDeleteEventArgs Obiekt, który zawiera dane zdarzenia.

Przykłady

W poniższym przykładzie pokazano, jak programowo dodać GridViewDeleteEventHandler delegata do RowDeleting zdarzenia kontrolki GridView .


<%@ 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(Object sender, EventArgs e)
  {
        
    // Create a new GridView control.
    GridView customersGridView = new GridView();
         
    // Set the GridView control's properties.          
    customersGridView.ID = "CustomersGridView";
    customersGridView.DataSourceID = "CustomersSqlDataSource"; 
    customersGridView.AutoGenerateColumns = true;
    customersGridView.AutoGenerateDeleteButton = true;
    customersGridView.DataKeyNames = new String[] {"CustomerID"};
       
    // Programmatically register the event-handling methods.
    customersGridView.RowDeleting += new GridViewDeleteEventHandler(this.CustomersGridView_RowDeleting);
        
    // Add the GridView object to the Controls collection
    // of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customersGridView);
        
  }
    
  void CustomersGridView_RowDeleting(Object sender, GridViewDeleteEventArgs e)
  {

    // User the sender parameter to retrieve the GridView control
    // that raised the event.
    GridView customersGridView = (GridView)sender;
    
    // Cancel the delete operation if the user attempts to remove
    // the last record from the GridView control.
    if (customersGridView.Rows.Count <= 1)
    {
        
      e.Cancel = true;
      Message.Text = "You must keep at least one record.";
            
    }
    
  }  

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewDeleteEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewDeleteEventHandler Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"          
        runat="server"/>
                
      <br/>
      
      <asp:placeholder id="GridViewPlaceHolder"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        deletecommand="Delete from Customers where CustomerID = @CustomerID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </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(ByVal sender As Object, ByVal e As EventArgs)
            
    ' Create a new GridView control.
    Dim customersGridView As New GridView()
         
    ' Set the GridView control's properties.          
    customersGridView.ID = "CustomersGridView"
    customersGridView.DataSourceID = "CustomersSqlDataSource"
    customersGridView.AutoGenerateColumns = True
    customersGridView.AutoGenerateDeleteButton = True
    Dim keyArray() As String = {"CustomerID"}
    customersGridView.DataKeyNames = keyArray
       
    ' Programmatically register the event-handling methods.
    AddHandler customersGridView.RowDeleting, AddressOf CustomersGridView_RowDeleting
        
    ' Add the GridView object to the Controls collection
    ' of the PlaceHolder control.
    GridViewPlaceHolder.Controls.Add(customersGridView)
        
  End Sub
    
  Sub CustomersGridView_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs)

    ' User the sender parameter to retrieve the GridView control
    ' that raised the event.
    Dim customersGridView As GridView = CType(sender, GridView)
    
    ' Cancel the delete operation if the user attempts to remove
    ' the last record from the GridView control.
    If customersGridView.Rows.Count <= 1 Then

      e.Cancel = True
      Message.Text = "You must keep at least one record."
            
    End If
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewDeleteEventHandler Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewDeleteEventHandler Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"          
        runat="server"/>
                
      <br/>
      
      <asp:placeholder id="GridViewPlaceHolder"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        deletecommand="Delete from Customers where CustomerID = @CustomerID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
      
    </form>
  </body>
</html>

W poniższym przykładzie pokazano, jak deklaratywnie dodać GridViewDeleteEventHandler delegata do RowDeleting zdarzenia kontrolki GridView .


<%@ 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 CustomersGridView_RowDeleting
        (Object sender, GridViewDeleteEventArgs e)
    {
        TableCell cell = CustomersGridView.Rows[e.RowIndex].Cells[2];
        if (cell.Text == "Beaver")
        {
            e.Cancel = true;
            Message.Text = "You cannot delete customer Beaver.";
        }
        else
        {
            Message.Text = "";
        }
    }  

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>GridView RowDeleting Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <h3>
        GridView RowDeleting Example
    </h3>
    <asp:Label ID="Message" ForeColor="Red" runat="server" />
    <br />
    <asp:GridView ID="CustomersGridView" runat="server" 
        DataSourceID="CustomersSqlDataSource" 
        AutoGenerateColumns="False"
        AutoGenerateDeleteButton="True" 
        OnRowDeleting="CustomersGridView_RowDeleting"
        DataKeyNames="CustomerID,AddressID">
        <Columns>
            <asp:BoundField DataField="FirstName" 
                HeaderText="FirstName" SortExpression="FirstName" />
            <asp:BoundField DataField="LastName" HeaderText="LastName" 
                SortExpression="LastName" />
            <asp:BoundField DataField="City" HeaderText="City" 
                SortExpression="City" />
            <asp:BoundField DataField="StateProvince" HeaderText="State" 
                SortExpression="StateProvince" />
        </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="CustomersSqlDataSource" runat="server"
        SelectCommand="SELECT SalesLT.CustomerAddress.CustomerID, 
            SalesLT.CustomerAddress.AddressID, 
            SalesLT.Customer.FirstName, 
            SalesLT.Customer.LastName, 
            SalesLT.Address.City, 
            SalesLT.Address.StateProvince 
            FROM SalesLT.Customer 
            INNER JOIN SalesLT.CustomerAddress 
            ON SalesLT.Customer.CustomerID = 
                SalesLT.CustomerAddress.CustomerID 
            INNER JOIN SalesLT.Address ON SalesLT.CustomerAddress.AddressID = 
                SalesLT.Address.AddressID"
        DeleteCommand="Delete from SalesLT.CustomerAddress where CustomerID = 
            @CustomerID and AddressID = @AddressID" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>">
        <DeleteParameters>
            <asp:Parameter Name="AddressID" />
            <asp:Parameter Name="CustomerID" />
        </DeleteParameters>
    </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">

    Private Sub CustomersGridView_RowDeleting _
        (ByVal sender As [Object], _
        ByVal e As GridViewDeleteEventArgs)
        Dim cell As TableCell
        cell = CustomersGridView.Rows(e.RowIndex).Cells(2)
        If cell.Text = "Beaver" Then
            e.Cancel = True
            Message.Text = "You cannot delete customer Beaver."
        Else
            Message.Text = ""
        End If
    End Sub
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>GridView RowDeleting Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <h3>
        GridView RowDeleting Example
    </h3>
    <asp:Label ID="Message" ForeColor="Red" runat="server" />
    <br />
    <asp:GridView ID="CustomersGridView" runat="server" 
        DataSourceID="CustomersSqlDataSource" 
        AutoGenerateColumns="False"
        AutoGenerateDeleteButton="True" 
        OnRowDeleting="CustomersGridView_RowDeleting"
        DataKeyNames="CustomerID,AddressID">
        <Columns>
            <asp:BoundField DataField="FirstName" 
                HeaderText="FirstName" SortExpression="FirstName" />
            <asp:BoundField DataField="LastName" HeaderText="LastName" 
                SortExpression="LastName" />
            <asp:BoundField DataField="City" HeaderText="City" 
                SortExpression="City" />
            <asp:BoundField DataField="StateProvince" HeaderText="State" 
                SortExpression="StateProvince" />
        </Columns>
    </asp:GridView>
    <asp:SqlDataSource ID="CustomersSqlDataSource" runat="server"
        SelectCommand="SELECT SalesLT.CustomerAddress.CustomerID, 
            SalesLT.CustomerAddress.AddressID, 
            SalesLT.Customer.FirstName, 
            SalesLT.Customer.LastName, 
            SalesLT.Address.City, 
            SalesLT.Address.StateProvince 
            FROM SalesLT.Customer 
            INNER JOIN SalesLT.CustomerAddress 
            ON SalesLT.Customer.CustomerID = 
                SalesLT.CustomerAddress.CustomerID 
            INNER JOIN SalesLT.Address ON SalesLT.CustomerAddress.AddressID = 
                SalesLT.Address.AddressID"
        DeleteCommand="Delete from SalesLT.CustomerAddress where CustomerID = 
            @CustomerID and AddressID = @AddressID" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>">
        <DeleteParameters>
            <asp:Parameter Name="AddressID" />
            <asp:Parameter Name="CustomerID" />
        </DeleteParameters>
    </asp:SqlDataSource>
    </form>
</body>
</html>

Uwagi

Kontrolka GridView zgłasza zdarzenie po kliknięciu RowDeleting przycisku Usuń (przycisku z jego CommandName właściwością na wartość "Usuń"), ale przed GridView usunięciem rekordu przez kontrolkę. Dzięki temu można podać metodę obsługi zdarzeń, która wykonuje niestandardową procedurę, taką jak anulowanie operacji usuwania, za każdym razem, gdy wystąpi to zdarzenie.

Podczas tworzenia delegata GridViewDeleteEventHandler należy zidentyfikować metodę, która będzie obsługiwać zdarzenie. Aby skojarzyć zdarzenie z programem obsługi zdarzeń, dodaj wystąpienie delegata do zdarzenia. Program obsługi zdarzeń jest wywoływany przy każdym wystąpieniu zdarzenia, o ile nie usunięto delegata. Aby uzyskać więcej informacji na temat delegatów programu obsługi zdarzeń, zobacz Obsługa i podnoszenie zdarzeń.

Metody rozszerzania

GetMethodInfo(Delegate)

Pobiera obiekt reprezentujący metodę reprezentowaną przez określonego delegata.

Dotyczy

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