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GridView.SelectedIndexChanging Zdarzenie

Definicja

Występuje po kliknięciu przycisku Select wiersza, ale zanim GridView kontrolka obsłuży operację wybierania.

public:
 event System::Web::UI::WebControls::GridViewSelectEventHandler ^ SelectedIndexChanging;
public event System.Web.UI.WebControls.GridViewSelectEventHandler SelectedIndexChanging;
member this.SelectedIndexChanging : System.Web.UI.WebControls.GridViewSelectEventHandler 
Public Custom Event SelectedIndexChanging As GridViewSelectEventHandler 

Typ zdarzenia

Przykłady

W poniższym przykładzie pokazano, jak za pomocą SelectedIndexChanging zdarzenia anulować operację wybierania.


<%@ 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_SelectedIndexChanged(Object sender, EventArgs e)
  {
    // Get the currently selected row using the SelectedRow property.
    GridViewRow row = CustomersGridView.SelectedRow;
        
    // Display the first name from the selected row.
    // In this example, the third column (index 2) contains
    // the first name.
    MessageLabel.Text = "You selected " + row.Cells[2].Text + ".";
  }

  void CustomersGridView_SelectedIndexChanging(Object sender, GridViewSelectEventArgs e)
  {
    // Get the currently selected row. Because the SelectedIndexChanging event
    // occurs before the select operation in the GridView control, the
    // SelectedRow property cannot be used. Instead, use the Rows collection
    // and the NewSelectedIndex property of the e argument passed to this 
    // event handler.
    GridViewRow row = CustomersGridView.Rows[e.NewSelectedIndex];

    // You can cancel the select operation by using the Cancel
    // property. For this example, if the user selects a customer with 
    // the ID "ANATR", the select operation is canceled and an error message
    // is displayed.
    if (row.Cells[1].Text == "ANATR")
    {
      e.Cancel = true;
      MessageLabel.Text = "You cannot select " + row.Cells[2].Text + "."; 
    }
  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridView Select Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
     <h3>GridView Select Example</h3>

     <asp:gridview id="CustomersGridView" 
       datasourceid="CustomersSource" 
       autogeneratecolumns="False"
       autogenerateselectbutton="True"
       selectedindex="1"
       onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
       onselectedindexchanging="CustomersGridView_SelectedIndexChanging"   
       runat="server" DataKeyNames="CustomerID">
                
         <Columns>
             <asp:BoundField DataField="CustomerID" 
                 HeaderText="CustomerID" 
                 InsertVisible="False" ReadOnly="True" 
                 SortExpression="CustomerID" />
             <asp:BoundField DataField="FirstName" 
                 HeaderText="FirstName" 
                 SortExpression="FirstName" />
             <asp:BoundField DataField="MiddleName" 
                 HeaderText="MiddleName" 
                 SortExpression="MiddleName" />
             <asp:BoundField DataField="LastName" 
                 HeaderText="LastName" 
                 SortExpression="LastName" />
             <asp:BoundField DataField="Phone" 
                 HeaderText="Phone" 
                 SortExpression="Phone" />
         </Columns>
                
       <selectedrowstyle backcolor="LightCyan"
         forecolor="DarkBlue"
         font-bold="true"/>  
                
     </asp:gridview>
            
      <br/>
            
      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSource"
        selectcommand="SELECT CustomerID, FirstName, MiddleName, LastName, Phone FROM SalesLT.Customer"
        connectionstring="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>" 
        runat="server"/>
            
    </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 CustomersGridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
        
    ' Get the currently selected row using the SelectedRow property.
    Dim row As GridViewRow = CustomersGridView.SelectedRow
        
    ' Display the first name from the selected row.
    ' In this example, the third column (index 2) contains
    ' the first name.
    MessageLabel.Text = "You selected " & row.Cells(2).Text & "."
  End Sub

  Sub CustomersGridView_SelectedIndexChanging(ByVal sender As Object, ByVal e As GridViewSelectEventArgs)
        
    ' Get the currently selected row. Because the SelectedIndexChanging event
    ' occurs before the select operation in the GridView control, the
    ' SelectedRow property cannot be used. Instead, use the Rows collection
    ' and the NewSelectedIndex property of the e argument passed to this 
    ' event handler.
    Dim row As GridViewRow = CustomersGridView.Rows(e.NewSelectedIndex)

    ' You can cancel the select operation by using the Cancel
    ' property. For this example, if the user selects a customer with 
    ' the ID "ANATR", the select operation is canceled and an error message
    ' is displayed.
    If row.Cells(1).Text = "ANATR" Then
        e.Cancel = True
        MessageLabel.Text = "You cannot select " + row.Cells(2).Text & "."
    End If
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridView Select Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
     <h3>GridView Select Example</h3>

     <asp:gridview id="CustomersGridView" 
       datasourceid="CustomersSource" 
       autogeneratecolumns="False"
       autogenerateselectbutton="True"
       selectedindex="1"
       onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
       onselectedindexchanging="CustomersGridView_SelectedIndexChanging"   
       runat="server" DataKeyNames="CustomerID">
                
         <Columns>
             <asp:BoundField DataField="CustomerID" 
                 HeaderText="CustomerID" 
                 InsertVisible="False" ReadOnly="True" 
                 SortExpression="CustomerID" />
             <asp:BoundField DataField="FirstName" 
                 HeaderText="FirstName" 
                 SortExpression="FirstName" />
             <asp:BoundField DataField="MiddleName" 
                 HeaderText="MiddleName" 
                 SortExpression="MiddleName" />
             <asp:BoundField DataField="LastName" 
                 HeaderText="LastName" 
                 SortExpression="LastName" />
             <asp:BoundField DataField="Phone" 
                 HeaderText="Phone" 
                 SortExpression="Phone" />
         </Columns>
                
       <selectedrowstyle backcolor="LightCyan"
         forecolor="DarkBlue"
         font-bold="true"/>  
                
     </asp:gridview>
            
      <br/>
            
      <asp:label id="MessageLabel"
        forecolor="Red"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSource"
        selectcommand="SELECT CustomerID, FirstName, MiddleName, LastName, Phone FROM SalesLT.Customer"
        connectionstring="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>" 
        runat="server"/>
            
    </form>

  </body>
</html>

Uwagi

Zdarzenie SelectedIndexChanging jest wywoływane po kliknięciu przycisku Wybierz wiersza, ale zanim GridView kontrolka obsłuży operację wybierania. Dzięki temu można podać metodę obsługi zdarzeń, która wykonuje niestandardową procedurę, taką jak anulowanie operacji wyboru, za każdym razem, gdy wystąpi to zdarzenie.

Uwaga

To zdarzenie nie jest zgłaszane podczas programowego ustawiania SelectedIndex właściwości.

GridViewSelectEventArgs Obiekt jest przekazywany do metody obsługi zdarzeń, która umożliwia określenie indeksu wiersza wybranego przez użytkownika i wskazanie, że operacja wyboru powinna zostać anulowana. Aby anulować operację wyboru, ustaw Cancel właściwość GridViewSelectEventArgs obiektu na true.

Aby uzyskać więcej informacji na temat obsługi zdarzeń, zobacz Obsługa i podnoszenie zdarzeń.

Dotyczy

Zobacz też