Hi,
I'm new to C Sharp and have been trying these peices of codes below and i get the subject error above. I'm trying to modify a web.config.
Please kindly help me point out which line causes the error.
*************************
Target Framwork: .NET 3.5
C Sharp
Visual Studio 2010
*************************
Thanks in advance.
Nel
Sample appSettings Web.Config File
ASPX Page
Code Behind
Error Message in Line 36
I'm new to C Sharp and have been trying these peices of codes below and i get the subject error above. I'm trying to modify a web.config.
Please kindly help me point out which line causes the error.
*************************
Target Framwork: .NET 3.5
C Sharp
Visual Studio 2010
*************************
Thanks in advance.
Nel
Sample appSettings Web.Config File
Code:
<appSettings>
<add key="Under Maintenance" value="N"/>
</appSettings>ASPX Page
Code:
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Admin.aspx.cs" Inherits="OCPSearchCSharp.Admin" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "[URL unfurl="true"]http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">[/URL]
<html xmlns="[URL unfurl="true"]http://www.w3.org/1999/xhtml">[/URL]
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="Button1" runat="server" onclick="Button1_Click"
Text="Update Web.Config" />
</div>
</form>
</body>
</html>Code Behind
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml;
using System.Configuration;
using System.Configuration.Assemblies;
using System.Configuration.Internal;
using System.Configuration.Provider;
namespace OCPSearchCSharp
{
public partial class Admin : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
//XmlElement element = xmlDoc.DocumentElement;
foreach (XmlElement element in xmlDoc.DocumentElement)
{
if (element.Name.Equals("appSettings"))
{
foreach (XmlNode node in element.ChildNodes)
{
if (node.Attributes[0].Value.Equals("Under Maintenance"))
{
node.Attributes[1].Value = "Yes";
Response.Write("<BR><BR>Hello World<BR><BR>");
}
}
}
}
xmlDoc.Save(AppDomain.CurrentDomain.SetupInformation.ConfigurationFile);
System.Configuration.ConfigurationManager.RefreshSection("appSettings");
}
}
}Error Message in Line 36
Code:
Server Error in '/' Application.
--------------------------------------------------------------------------------
Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
Line 34: foreach (XmlNode node in element.ChildNodes)
Line 35: {
Line 36: if (node.Attributes[0].Value.Equals("Under Maintenance"))
Line 37: {
Line 38: node.Attributes[1].Value = "Yes";
Source File: C:\Data\OCPSearchCSharp\OCPSearchCSharp\OCPSearchCSharp\Admin.aspx.cs Line: 36
Stack Trace:
[NullReferenceException: Object reference not set to an instance of an object.]
OCPSearchCSharp.Admin.Button1_Click(Object sender, EventArgs e) in C:\Data\OCPSearchCSharp\OCPSearchCSharp\OCPSearchCSharp\Admin.aspx.cs:36
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565