ASP.Net - How do I programatically edit external config files at runtime

Question

By external config files, I mean .config files other than web.config. I've seen all the examples on how to edit web.config at runtime, but I want to edit a config file referenced by a configSource for appSettings. I want to modify only the external file and I will handle the app recycle.

Ideally I would like to use a built-in class to deal with the edits, but if the only option is a manual File open/parse, etc, then sobeit.

The general idea behind all this being a Settings page that is viewed at app startup, user sets their particulars and then saves the changes, then the real app starts up. quick and easy install app/configure page, so I'd like to leverage .config if at all possible.

Thanks!

FOLLOWUP - Quick Snippet to use XmlDocument to change an appSetting key value:

string path = Server.MapPath("~/my.config");

XmlDocument doc = new XmlDocument();
doc.Load(path);

XmlNode node = doc.SelectSingleNode("/appSettings/add[@key='myKey']");
node.Attributes[1].Value = "myVal";

XmlTextWriter writer = new XmlTextWriter(path, null);
writer.Formatting = Formatting.Indented;
doc.WriteTo(writer);
writer.Flush();
writer.Close();

Answer 1

The usual code for editing standard configuration files goes like this:

string cfgPath = Path.Combine(targetDir, "myApp.config");
var configMap = new ExeConfigurationFileMap { ExeConfigFilename = cfgPath };

var cf = ConfigurationManager.OpenMappedExeConfiguration(configMap,
    ConfigurationUserLevel.None);
cf.AppSettings.Settings["somekey"].Value = "newvalue";

cf.Save();

Code version is .NET 3.5, by the way.

You probably need to set the correct permissions as well. Note that if you don't have the standard configuration file layout (root node is <configuration>) this code will throw an exception.

Answer 2

You should, at the very least, be able to utilize the classes in the System.Xml Namespace to read the settings files as any old XML file.