Updated on Kisan Patel
This tutorial will explain you how to read and write AppSettings value from ASP.NET web.config file.
The <appSettings> element stores custom application configuration settings.
<appSettings> <add key="KeyName" value="KeyValue" /> </appSettings>
The key/value pairs specified in the <appSettings> element can be accessed in code using the System.Configuration.ConfigurationSettings class.
string value = WebConfigurationManager.AppSettings["KeyName"];
To modify Key Value, first you need to obtain configuration settings for the root-level using OpenWebConfiguration method. To update a configuration setting, use the Save or SaveAs method of the configuration object.
//Helps to open the Root level web.config file.
Configuration webConfigApp = WebConfigurationManager.OpenWebConfiguration("~");
//Modifying the AppKey from AppValue to AppValue1
webConfigApp.AppSettings.Settings["KeyName"].Value = "KeyValue";
//Save the Modified settings of AppSettings.
webConfigApp.Save();
Lets take example to understand how to read and write <appSettings>.
First Defined AppSettings Section in Web.Config file as shown below code:
web.config
<configuration>
...
<appSettings>
<add key="BackgroundColor" value="Red"/>
</appSettings>
</configuration>
Now, add below line of code to Default.aspx page. here we have added one txt_bgColor TextBox and btn_save button. In this demo, we change the background color of the page by adding or changing bgcolor attribute value of the
Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebAppSettingDemo.Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body id="PageBody" runat="server">
<form id="form1" runat="server">
<div>
<asp:Label ID="lbl_bgColor" runat="server" Text="Color Name: "></asp:Label>
<asp:TextBox ID="txt_bgColor" runat="server"></asp:TextBox>
</div>
<asp:Button ID="btn_Save" runat="server" Text="Change Color" OnClick="btn_Save_Click" />
</form>
</body>
</html>
Now, add below line of code to Default.aspx.cs page
using System;
using System.Configuration;
using System.Web.Configuration;
namespace WebAppSettingDemo
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
PageBody.Attributes.Add("bgcolor", WebConfigurationManager.AppSettings["BackgroundColor"]);
}
}
protected void btn_Save_Click(object sender, EventArgs e)
{
//Helps to open the Root level web.config file.
Configuration webConfigApp = WebConfigurationManager.OpenWebConfiguration("~");
//Modifying the AppKey from AppValue to AppValue1
webConfigApp.AppSettings.Settings["BackgroundColor"].Value = txt_bgColor.Text;
//Save the Modified settings of AppSettings.
webConfigApp.Save();
Response.Redirect(Request.RawUrl);
}
}
}
Demo
