.NET Custom Configuration Section, Collection and Elements

01 Feb 2012

This site about writing custom configurationsection offers the most straight forward solution. Make sure you implement all methods the author describes for your version of the ConfigurationElementCollection class. I tried just the ones the abstract class requires but could not get it to work. I've posted my own implementation using the authors guidelines to create a configuration collection of jobs.

Another useful link from a stackoverflow question.

App.Config

<?xml version="1.0"?>
<configuration>
  <configSections>
    <section name="jobSection"
      type="MyConfiguration.JobSection, MyConfiguration" />
  </configSections>
  <jobSection>
    <jobs>
      <job id="1" name="Job Name A" />
      <job id="2" name="Job Name B" />
    </jobs>
  </jobSection>
</configuration>

My C# classes

namespace MyConfiguration
{
    public class JobElement : ConfigurationElement
    {
        [ConfigurationProperty("id", IsRequired = true, IsKey = true)]
        public int Id
        {
            get { return (int)base["id"]; }
        }

        [ConfigurationProperty("name", IsRequired = false)]
        public string Name
        {
            get { return (string)base["name"]; }
        }
    }

    [ConfigurationCollection(typeof(JobElement))]
    public class JobElementCollection : ConfigurationElementCollection
    {
        internal const string PropertyName = "job";

        public override ConfigurationElementCollectionType CollectionType
        {
            get
            {
                return ConfigurationElementCollectionType.BasicMapAlternate;
            }
        }
        protected override string ElementName
        {
            get
            {
                return PropertyName;
            }
        }

        protected override bool IsElementName(string elementName)
        {
            return elementName.Equals(PropertyName,
              StringComparison.InvariantCultureIgnoreCase);
        }

        public override bool IsReadOnly()
        {
            return false;
        }

        protected override ConfigurationElement CreateNewElement()
        {
            return new JobElement();
        }

        protected override object GetElementKey(ConfigurationElement element)
        {
            return ((JobElement)(element)).Id;
        }

        public JobElement this[int idx]
        {
            get { return (JobElement)BaseGet(idx); }
        }
    }

    public class JobSection : ConfigurationSection
    {
        [ConfigurationProperty("jobs")]
        public JobElementCollection Jobs
        {
            get { return ((JobElementCollection)(base["jobs"])); }
            set { base["jobs"] = value; }
        }
    }
}

C# Code to reference config

var section = ConfigurationManager.GetSection("jobSection");
if (section != null)
{
    var jobs = (section as JobSection).Jobs;
    Console.WriteLine(jobs.Count);
    for (int i = 0; i < jobs.Count; i++)
    {
        Console.WriteLine("{0} - {1}", jobs[i].Id, jobs[i].Name);
    }
}