IConfigurationSectionHandler example

January 01, 2010

This is a small snippet for the basics of writing a ConfigurationHandler to read a configuration section from your web.config or app.config. Since I wrote this I’ve moved to the easier ConfigSection way of doing things, there’s an example here.

You start off with the XML definition in the config file:

	<configSections>
	<section name="mysection" type="MyNamespace.ConfigurationHandler,Mynamespace" />
	</configSections>
	<mysection>
	<security enabled="true" />
	<username>bob</username>
	</mysection>

view raw gistfile1.xml hosted with ❤ by GitHub

And then define your own parser class, and a Settings class to store the details in:

	public class ConfigurationHandler : IConfigurationSectionHandler
	{
	/// <summary>
	/// Creates a <see cref="Settings"/> object from the configuration file.
	/// </summary>
	/// <seealso cref="Settings"/>
	public object Create(object parent, object configContext, System.Xml.XmlNode section)
	{
	if (section == null)
	throw new ArgumentNullException("'section' is null. Check your app.config or web.config exists and is valid.");
	try
	{
	Settings settings = new Settings();
	// Security
	XmlNode node = section.SelectSingleNode("//security");
	if (node != null)
	Settings.Security = (node.Attributes["enabled"].Value == "true");
	else
	throw new Exception("No security node could be found in the web/app.config");
	// Username
	node = section.SelectSingleNode("//username");
	if (node != null)
	settings.Username = node.Value;
	else
	throw new Exception("No username could be found in the web/app.config");
	return settings;
	}
	catch (XPathException ex)
	{
	// Catch From SelectSingleNode,SelectNodes
	throw new Exception("XPathException caught when reading config file", ex);
	}
	}
	}

	public class Settings
	{
	public bool Security { get; set; }
	public string Username { get; set; }
	}

view raw gistfile1.cs hosted with ❤ by GitHub

And then when you application first initializes, read the settings like so:

var settings = (Settings)ConfigurationManager.GetSection("mysection");

An alternative way of doing this is to make the Settings class responsible for initializing itself inside a static constructor, using the above line. You would then make the Settings class a singleton.

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I'm Chris Small, a software engineer working in London. This is my tech blog. Find out more about me via Github, Stackoverflow, Resume