Changing the value of web.config file runtime

There is pretty small and simple code to change the value of key defined in web.config file.

// Get the reference of the configuration file at the root.
Configuration objConfig = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
// Change the value of one key
Response.Write(string.Format("Old value : {0}<br/>", objConfig.AppSettings.Settings["MyKey"].Value));
objConfig.AppSettings.Settings["MyKey"].Value = "changed web config";
// Save the changes.
objConfig.Save();
Response.Write(string.Format("New value : {0}", objConfig.AppSettings.Settings["MyKey"].Value));