Edit

GridView.OnSelectedIndexChanged(EventArgs) Method

  • Reference

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Raises the SelectedIndexChanged event.

protected:
 virtual void OnSelectedIndexChanged(EventArgs ^ e);
protected virtual void OnSelectedIndexChanged (EventArgs e);
abstract member OnSelectedIndexChanged : EventArgs -> unit
override this.OnSelectedIndexChanged : EventArgs -> unit
Protected Overridable Sub OnSelectedIndexChanged (e As EventArgs)

Parameters

e
EventArgs

An EventArgs that contains event data.

Examples

The following example shows how create an event handler for the SelectedIndexChanged event. In this example, the selected row is persisted in the view state. So even after a sorting or a paging operation, only that row will be selected.

<%@ 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">

  protected void ContactsGridView_SelectedIndexChanged(object sender, EventArgs e)
  {
    if (ContactsGridView.SelectedIndex >= 0)
      ViewState["SelectedKey"] = ContactsGridView.SelectedValue;
    else
      ViewState["SelectedKey"] = null;
  }

  protected void ContactsGridView_DataBound(object sender, EventArgs e)
  {
    for (int i = 0; i < ContactsGridView.Rows.Count; i++)
    {
      // Ignore values that cannot be cast as integer.
      try
      {
        if ((int)ContactsGridView.DataKeys[i].Value == (int)ViewState["SelectedKey"])
          ContactsGridView.SelectedIndex = i;
      }
      catch { }
    }
  }

  protected void ContactsGridView_Sorting(object sender, GridViewSortEventArgs e)
  {
    ContactsGridView.SelectedIndex = -1;
  }

  protected void ContactsGridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
  {
    ContactsGridView.SelectedIndex = -1;
  }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>GridView OnSelectedIndexChanged Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridView OnSelectedIndexChanged Example</h3>
      
      <asp:GridView ID="ContactsGridView"
        DataSourceID="ContactsDataSource" 
        DataKeyNames="ContactID"        
        AutoGenerateSelectButton="True"
        OnSelectedIndexChanged="ContactsGridView_SelectedIndexChanged"        
        AllowPaging="True" AllowSorting="True" 
        OnDataBound="ContactsGridView_DataBound" 
        OnSorting="ContactsGridView_Sorting" 
        OnPageIndexChanging="ContactsGridView_PageIndexChanging"
        runat="server">
        <SelectedRowStyle BackColor="Aqua" />
      </asp:GridView>
            
      <!-- This example uses Microsoft SQL Server and connects      -->
      <!-- to the AdventureWorks sample database. Use an ASP.NET    -->
      <!-- expression to retrieve the connection string value       -->
      <!-- from the Web.config file.                                -->
      <asp:SqlDataSource ID="ContactsDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ContactID], [FirstName], [LastName] FROM Person.Contact">
      </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">

  Protected Sub ContactsGridView_SelectedIndexChanged()
    If ContactsGridView.SelectedIndex >= 0 Then
      ViewState("SelectedKey") = ContactsGridView.SelectedValue
    Else
      ViewState("SelectedKey") = Nothing
    End If
  End Sub

  Protected Sub ContactsGridView_DataBound()
    For i As Integer = 0 To ContactsGridView.Rows.Count - 1
      ' Ignore values that cannot be cast as integer.
      Try
        If Convert.ToInt32(ContactsGridView.DataKeys(i).Value) = Convert.ToInt32(ViewState("SelectedKey")) Then _
          ContactsGridView.SelectedIndex = i
      Catch
      End Try
    Next
  End Sub

  Protected Sub ContactsGridView_Sorting()
    ContactsGridView.SelectedIndex = -1
  End Sub

  Protected Sub ContactsGridView_PageIndexChanging()
    ContactsGridView.SelectedIndex = -1
  End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>GridView OnSelectedIndexChanged Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridView OnSelectedIndexChanged Example</h3>
      
      <asp:GridView ID="ContactsGridView"
        DataSourceID="ContactsDataSource" 
        DataKeyNames="ContactID"        
        AutoGenerateSelectButton="True"
        OnSelectedIndexChanged="ContactsGridView_SelectedIndexChanged"        
        AllowPaging="True" AllowSorting="True" 
        OnDataBound="ContactsGridView_DataBound" 
        OnSorting="ContactsGridView_Sorting" 
        OnPageIndexChanging="ContactsGridView_PageIndexChanging"
        runat="server">
        <SelectedRowStyle BackColor="Aqua" />
      </asp:GridView>
            
      <!-- This example uses Microsoft SQL Server and connects      -->
      <!-- to the AdventureWorks sample database. Use an ASP.NET    -->
      <!-- expression to retrieve the connection string value       -->
      <!-- from the Web.config file.                                -->
      <asp:SqlDataSource ID="ContactsDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [ContactID], [FirstName], [LastName] FROM Person.Contact">
      </asp:SqlDataSource>


    </form>
  </body>
</html>

Remarks

The SelectedIndexChanged event is raised when a row's Select button is clicked, but after the GridView control handles the select operation. This enables you to provide an event-handling method that performs a custom routine, such as updating a status label with the currently selected row, whenever this event occurs.

Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.

The OnSelectedIndexChanged method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors

When overriding OnSelectedIndexChanged(EventArgs) in a derived class, be sure to call the base class's OnSelectedIndexChanged(EventArgs) method so that registered delegates receive the event.

Applies to

See also