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GridViewSelectEventHandler Delegate

Represents the method that handles the SelectedIndexChanging event of a GridView control.

Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)

public delegate void GridViewSelectEventHandler (
	Object sender,
	GridViewSelectEventArgs e
)
/** @delegate */
public delegate void GridViewSelectEventHandler (
	Object sender, 
	GridViewSelectEventArgs e
)
Not applicable.

Parameters

sender

The source of the event.

e

A GridViewSelectEventArgs object that contains the event data.

The SelectedIndexChanging event is raised when a Select button (a button with its CommandName property set to "Select") is clicked, but before the GridView control handles the select operation. This allows you to provide an event-handling method that performs a custom routine, such as canceling the selection operation, whenever this event occurs.

When you create a GridViewSelectEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

The following example demonstrates how to programmatically add a GridViewSelectEventHandler delegate to the SelectedIndexChanging event of a GridView control.


<%@ 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>


The following example demonstrates how to declaratively add a GridViewSelectEventHandler delegate to the SelectedIndexChanging event of a GridView control.


<%@ 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 company name from the selected row.
    // In this example, the third column (index 2) contains
    // the company name.
    Message.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;
      Message.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="true"
       autogenerateselectbutton="true"
       allowpaging="true" 
       selectedindex="0"
       onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
       onselectedindexchanging="CustomersGridView_SelectedIndexChanging"   
       runat="server">
                
       <selectedrowstyle backcolor="LightCyan"
         forecolor="DarkBlue"
         font-bold="true"/>  
                
     </asp:gridview>
            
      <br/>
            
      <asp:label id="Message"
        forecolor="Red"
        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="CustomersSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
        runat="server"/>
            
    </form>
  </body>
</html>


Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0
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