Ler en inglés

Compartir por

GridViewSelectEventHandler Delegado

  • Referencia

Definición

Espacio de nombres:
System.Web.UI.WebControls
Ensamblado:
System.Web.dll

Representa el método que controla el evento SelectedIndexChanging de un control GridView.

C# 
public delegate void GridViewSelectEventHandler(object sender, GridViewSelectEventArgs e);

Parámetros

sender
Object

Origen del evento.

e
GridViewSelectEventArgs

Objeto GridViewSelectEventArgs que contiene los datos del evento.

Ejemplos

En el ejemplo siguiente se muestra cómo agregar mediante programación un GridViewSelectEventHandler delegado al SelectedIndexChanging evento de un GridView control .

ASP.NET (C#) 

<%@ 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 object.
        GridView authorGridView = new GridView();
         
        // Set the GridView object's properties.
        authorGridView.ID = "AuthorGridView";
        authorGridView.DataSourceID = "AuthorsSqlDataSource"; 
        authorGridView.AutoGenerateColumns = true;
        authorGridView.AutoGenerateSelectButton = true;
        authorGridView.AllowPaging = true; 
        authorGridView.SelectedIndex = 1;
        authorGridView.SelectedRowStyle.BackColor = System.Drawing.Color.LightCyan;
        authorGridView.SelectedRowStyle.ForeColor = System.Drawing.Color.DarkBlue;
        authorGridView.SelectedRowStyle.Font.Bold = true;
        
        // Programmatically register the event-handling methods.
        authorGridView.SelectedIndexChanged += new EventHandler(this.AuthorsGridView_SelectedIndexChanged);
        authorGridView.SelectedIndexChanging += new GridViewSelectEventHandler(this.AuthorsGridView_SelectedIndexChanging);
        
        // Add the GridView object to the Controls collection
        // of the PlaceHolder control.
        GridViewPlaceHolder.Controls.Add(authorGridView);
        
    }
    
    void AuthorsGridView_SelectedIndexChanged(Object sender, EventArgs e)
    {
    
        // Get the currently selected row using the SelectedRow property.
        GridView AuthorsGridView = (GridView)sender;
        GridViewRow row = AuthorsGridView.SelectedRow;
        
        // Display the author's name from the selected row.
        // In this example, the second and third columns contain
        // the author's last and first name, respectively.
        Message.Text = "You selected " + row.Cells[2].Text +
            " " + row.Cells[1].Text + ".";
    
    }
    
    void AuthorsGridView_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.
        GridView AuthorsGridView = (GridView)sender;
        GridViewRow row = AuthorsGridView.Rows[e.NewSelectedIndex];
        
        // If the user selects an author with the last name White,
        // cancel the selection operation and display an error message.
        if(row.Cells[1].Text == "White")
        {
        
            e.Cancel = true;
            Message.Text = "You cannot select " + row.Cells[2].Text +
            " " + row.Cells[1].Text + ".";
        
        }
    
    }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
    <title>GridViewSelectEventHandler Example</title>
</head>
<body>
        <form id="form1" runat="server">
        
            <h3>GridViewSelectEventHandler Example</h3>
            
            <asp:placeholder id="GridViewPlaceHolder"
                runat="Server"/>
            
            <!-- This example uses Microsoft SQL Server and connects -->
            <!-- to the Pubs sample database.                         -->
            <asp:sqldatasource id="AuthorsSqlDataSource"  
                selectcommand="SELECT [au_lname], [au_fname], [address], [city], [state], [zip], [contract] FROM [authors]"
                connectionstring="server=localhost;database=pubs;integrated security=SSPI"
                runat="server">
            </asp:sqldatasource>
            
            <br/>
            
            <asp:label id="Message"
                runat="server"/>
            
        </form>
    </body>
</html>

En el ejemplo siguiente se muestra cómo agregar mediante declaración un GridViewSelectEventHandler delegado al SelectedIndexChanging evento de un GridView control .

ASP.NET (C#) 

<%@ 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>

Comentarios

El SelectedIndexChanging evento se genera cuando se hace clic en un botón Seleccionar (un botón con su CommandName propiedad establecida en "Seleccionar"), pero antes de que el GridView control control controle la operación de selección. Esto le permite proporcionar un método de control de eventos que realiza una rutina personalizada, como cancelar la operación de selección, siempre que se produzca este evento.

Cuando se crea un delegado GridViewSelectEventHandler, se identifica el método que controlará el evento. Para asociar el evento al controlador, se debe agregar una instancia del delegado al evento. Siempre que se produce el evento, se llama a su controlador, a menos que se quite el delegado. Para obtener más información sobre los delegados del controlador de eventos, vea Control y generación de eventos.

Métodos de extensión

GetMethodInfo(Delegate)

Obtiene un objeto que representa el método representado por el delegado especificado.

Se aplica a

Produto Versións
.NET Framework 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1

Consulte también