GridViewSelectEventHandler Delegate

Definition

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

public delegate void GridViewSelectEventHandler(System::Object ^ sender, GridViewSelectEventArgs ^ e);
public delegate void GridViewSelectEventHandler(object sender, GridViewSelectEventArgs e);
type GridViewSelectEventHandler = delegate of obj * GridViewSelectEventArgs -> unit
Public Delegate Sub GridViewSelectEventHandler(sender As Object, e As GridViewSelectEventArgs)

Parameters

sender
Object

The source of the event.

e
GridViewSelectEventArgs

A GridViewSelectEventArgs object that contains the event data.

Inheritance
GridViewSelectEventHandler

Examples

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>


<%@ 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 object.
        Dim authorGridView As GridView = 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.
        AddHandler authorGridView.SelectedIndexChanged, AddressOf AuthorsGridView_SelectedIndexChanged
        AddHandler authorGridView.SelectedIndexChanging, AddressOf AuthorsGridView_SelectedIndexChanging
        
        ' Add the GridView object to the Controls collection
        ' of the PlaceHolder control.
        GridViewPlaceHolder.Controls.Add(authorGridView)
        
    End Sub
    
    Sub AuthorsGridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

        ' Get the currently selected row using the SelectedRow property.
        Dim AuthorsGridView As GridView = CType(sender, GridView)
        Dim row As GridViewRow = 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 & "."
    
    End Sub
    
    Sub AuthorsGridView_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 AuthorsGridView As GridView = CType(sender, GridView)
        Dim row As GridViewRow = 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 & "."
        
        End If
    
    End Sub

</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 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>

Remarks

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 Handling and Raising Events.

Extension Methods

GetMethodInfo(Delegate)

Gets an object that represents the method represented by the specified delegate.

Applies to

See also