How to dynamically change connection string/appSetting in web.config

// Update AppSetting in web config

public void UpdateAppSetting(string key, string value)

{

    Configuration config = WebConfigurationManager.OpenWebConfiguration("~");

    if (config.AppSettings.Settings[key] == null)

    {

        config.AppSettings.Settings.Add(key, value);

    }

    else

    {

        config.AppSettings.Settings[key].Value = value;

    }

    config.Save();

    ConfigurationManager.RefreshSection("appSettings");

}

 

// Update connection string in web config

public void UpdateConnectionString(string key, string value)

{

    Configuration config = WebConfigurationManager.OpenWebConfiguration("~");

    if (config.ConnectionStrings.ConnectionStrings[key] == null)

    {

        config.ConnectionStrings.ConnectionStrings.Add(new ConnectionStringSettings(key, value));

    }

    else

    {

        config.ConnectionStrings.ConnectionStrings[key].ConnectionString = value;

    }

    config.Save();

    ConfigurationManager.RefreshSection("connectionStrings");

}

 

 

You can update the contents of web.cofig file by simply calling above functions like this:-

 

protected void Page_Load(object sender, EventArgs e)

{

    UpdateAppSetting("Country", "India");

    UpdateConnectionString("dbName", "dbSchool");

}