ConfigurationHandler snippet

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>

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

public class ConfigurationHandler : IConfigurationSectionHandler
{
    #region IConfigurationSectionHandler Members
    /// <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);
        }
    }

    #endregion
}

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

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.