How to add a sectionGroup into web.config programmatically

Question

Background

I want to insert the following into my web.config

  <sectionGroup name="elmah">
    <section name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah"/>
    <section name="errorLog" requirePermission="false" type="Elmah.ErrorLogSectionHandler, Elmah"/>
    <section name="errorMail" requirePermission="false" type="Elmah.ErrorMailSectionHandler, Elmah"/>
  </sectionGroup>

(no prizes for guessing what I am trying to achieve!) but I am getting thoroughly confused. The docs on MSDN suggest that I need to create a subclass of ConfurationSection if I want to add one to a group. I wrote myself a little windows application to help me figure it out but I did not get very far! Here is the pertinent code - which tries to add the just the "security" section.

private void AddElmahSectionGroup()
{
    string exePath = Path.Combine(Environment.CurrentDirectory, "NameOfExe.exe");
    Configuration configuration = ConfigurationManager.OpenExeConfiguration(exePath);

    ConfigurationSectionGroup elmahGroup = configuration.GetSectionGroup(elmahSectionGroupName);
    if (elmahGroup != null)
    {
        Console.WriteLine("sectionGroup with name {0} already in web.config", elmahSectionGroupName);
        return;
    }
    elmahGroup = new ConfigurationSectionGroup();
    configuration.SectionGroups.Add(elmahSectionGroupName, elmahGroup);

    var securitySection = new Section { Name = "security", RequirePermission = false, Type = "Elmah.SecuritySectionHandler, Elmah" };
    elmahGroup.Sections.Add("security", securitySection);

    configuration.Save();
}

public class Section : ConfigurationSection
{
    [ConfigurationProperty("name", IsRequired = true)]
    public string Name { get { return (String)this["name"]; } set { this["name"] = value; } }

    [ConfigurationProperty("requirePermission", IsRequired = true)]
    public bool RequirePermission { get { return (bool)this["requirePermission"]; } set { this["requirePermission"] = value; } }

    [ConfigurationProperty("type", IsRequired = true)]
    public string Type { get { return (string)this["type"]; } set { this["type"] = value; } }
}

And here is the resultant configuration file

    <?xml version="1.0" encoding="utf-8"?>
<configuration>
    <configSections>
        <sectionGroup name="elmah" type="System.Configuration.ConfigurationSectionGroup, System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" >
            <section name="security" type="ConfigEditing.Form1+ElmahLogic+Section, ConfigEditing, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" />
        </sectionGroup>
    </configSections>
    <elmah>
        <security name="security" requirePermission="false" type="Elmah.SecuritySectionHandler, Elmah" />
    </elmah>
</configuration>

Which completely twisted my melon: -

• first of all the type of the section element is the type of my class (derived from ConfigurationSection)
• second by adding a sectionGroup definition into the group, I (at the same time) adding the group into the config.

I am not really surprised by these findings because I really don't understand the API but I just have not found any decent docs about what I want to do. Can anyone here help - even if it just pointing me at an MSDN example that is an actual full working example.

Answer 1

A simple example that will add a section like the following to app.config:

//<configSections>
//  <sectionGroup name="elmah" type="Overflow.CustomConfigurationSectionGroup, Overflow, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" >
//  </sectionGroup>
//</configSections>

namespace Overflow
{
    public class CustomSecuritySection : ConfigurationSection
    {
    }

    public class CustomConfigurationSectionGroup : ConfigurationSectionGroup
    {
        public CustomConfigurationSectionGroup()
        {
            Security = new CustomSecuritySection();
        }

        [ConfigurationProperty("security")] 
        public CustomSecuritySection Security { get; private set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var config = ConfigurationManager.OpenExeConfiguration(Path.Combine(Application.StartupPath, Application.ProductName + ".exe"));

            config.SectionGroups.Add("elmah", new CustomConfigurationSectionGroup());

            config.Save(ConfigurationSaveMode.Modified);

        }
    }
}