Question

In the GridView, why I have to define select method in the same page instead of C# file ?

for example, in the index.aspx, I have

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="index.aspx.cs" Inherits="GridViewApp.index" %>     
<asp:GridView ID="GridView1" runat="server" 
          onselectedindexchanged="GridView1_SelectedIndexChanged" 
        DataSourceID="SqlDataSource2" AllowPaging="True" AllowSorting="True">
            <Columns>
                <asp:CommandField ShowSelectButton="True"  />
            </Columns>
        </asp:GridView>

GridView1_SelectedIndexChanged, this method have to be defined in the index.aspx instead of index.aspx.cs ?

The error message is

Compiler Error Message: CS1061: 'ASP.index_aspx' does not contain a definition for 'GridView1_SelectedIndexChanged' and no extension method 'GridView1_SelectedIndexChanged' accepting a first argument of type 'ASP.index_aspx' could be found (are you missing a using directive or an assembly reference?)

UPDATED:
resolve. after I clean the project, rebuild it. it works now. what is the correct way to build / debug a project ? how to clean cache ?

Appreciate your help.

Answer 1

The method GridView1_SelectedIndexChanged needs to be defined on the page that contains the GridView1 and make sure that you declare it at least as protected

protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
   //do magic
}