Correct implementation of a custom config section with nested collections?

Question

In a web application, I want to be able to define some mapping using a config section like this:

<configuration>
    <configSections>
        <sectionGroup name="MyCustomer">
            <section name="CatalogMappings" type="MyCustom.MyConfigSection" />
        </sectionGroup>
    </configSections>
    <MyCustomer>
        <catalogMappings>
            <catalog name="toto">
                <mapping value="1" displayText="titi" />
                <mapping value="2" displayText="tata" />
            </catalog>
            <catalog name="toto2">
                <mapping value="1" displayText="titi2" />
                <mapping value="2" displayText="tata2" />
            </catalog>
        </catalogMappings>
    </MyCustomer>
</configuration>

I'm struggling to achieve this goal, especially when defining my collection of collections. What are the classes that I need to implement to achieve this?

Currently, I have:

public class CatalogMappingSection : System.Configuration.ConfigurationSection
{
    public class Mapping : ConfigurationElement
    {
        [ConfigurationProperty("externalKey")]
        public string ExternalKey { get; set; }
        [ConfigurationProperty("displayText", IsRequired=true)]
        public string DisplayText { get; set; }
        [ConfigurationProperty("value", IsRequired=true, IsKey=true)]
        public int Value { get; set; }
    }

    public class Catalog : ConfigurationElementCollection
    {
        [ConfigurationProperty("name", IsRequired=true, IsKey=true)]
        public string Name { get; set; }

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

        protected override object GetElementKey(ConfigurationElement element)
        {
            return ((Mapping)element).Value;
        }
    }

    public class CatalogCollection : ConfigurationElementCollection
    {
        [ConfigurationProperty("catalog")]
        [ConfigurationCollection(typeof(Catalog))]
        public Catalog CatalogMappingCollection
        {
            get
            {
                return (Catalog)base["catalog"];
            }
        }

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

        protected override object GetElementKey(ConfigurationElement element)
        {
            return ((Catalog)element).Name;
        }
    }

    [ConfigurationProperty("catalogMappings")]
    [ConfigurationCollection(typeof(CatalogCollection))]
    public CatalogCollection CatalogMappings
    {
        get
        {
            return (CatalogCollection)base["catalogMappings"];
        }
    }
}

But, this is not working as expected.

Answer 1

I finally found this guy's example. It was coded and worked right out of the box.

http://manyrootsofallevilrants.blogspot.com/2011/07/nested-custom-configuration-collections.html

I am going to paste the code here......only because I cannot stand it when someone says "Your answer is here", and the link is dead.

Please try his website first, and leave a "thank you" if it works.

Note, I also have a "Usa-States and Usa-Counties" example (an answer to THIS SOF question) if you want a "more well known" (object model) example.

using System;
using System.Configuration;
 
namespace SSHTunnelWF
{
    public class TunnelSection : ConfigurationSection
    {
        [ConfigurationProperty("", IsDefaultCollection = true)]  
        public HostCollection Tunnels
        {
            get
            {
                HostCollection hostCollection = (HostCollection)base[""];
                return hostCollection;                
            }
        }
    }
 
    public class HostCollection : ConfigurationElementCollection
    {
        public HostCollection()
        {
            HostConfigElement details = (HostConfigElement)CreateNewElement();
            if (details.SSHServerHostname != "")
            {
                Add(details);
            }
        }
 
        public override ConfigurationElementCollectionType CollectionType
        {
            get
            {
                return ConfigurationElementCollectionType.BasicMap;
            }
        }
 
        protected override ConfigurationElement CreateNewElement()
        {
            return new HostConfigElement();
        }
 
        protected override Object GetElementKey(ConfigurationElement element)
        {
            return ((HostConfigElement)element).SSHServerHostname;
        }
 
        public HostConfigElement this[int index]
        {
            get
            {
                return (HostConfigElement)BaseGet(index);
            }
            set
            {
                if (BaseGet(index) != null)
                {
                    BaseRemoveAt(index);
                }
                BaseAdd(index, value);
            }
        }
 
        new public HostConfigElement this[string name]
        {
            get
            {
                return (HostConfigElement)BaseGet(name);
            }
        }
 
        public int IndexOf(HostConfigElement details)
        {
            return BaseIndexOf(details);
        }
 
        public void Add(HostConfigElement details)
        {
            BaseAdd(details);
        }

        protected override void BaseAdd(ConfigurationElement element)
        {
            BaseAdd(element, false);
        }
 
        public void Remove(HostConfigElement details)
        {
            if (BaseIndexOf(details) >= 0)
                BaseRemove(details.SSHServerHostname);
        }
 
        public void RemoveAt(int index)
        {
            BaseRemoveAt(index);
        }
 
        public void Remove(string name)
        {
            BaseRemove(name);
        }
 
        public void Clear()
        {
            BaseClear();
        }
 
        protected override string ElementName
        {
            get { return "host"; }
        }
    }
 
    public class HostConfigElement:ConfigurationElement
    {
        [ConfigurationProperty("SSHServerHostname", IsRequired = true, IsKey = true)]
        [StringValidator(InvalidCharacters = "  ~!@#$%^&*()[]{}/;’\"|\\")]
        public string SSHServerHostname
        {
            get { return (string)this["SSHServerHostname"]; }
            set { this["SSHServerHostname"] = value; }
        }
 
        [ConfigurationProperty("username", IsRequired = true)]
        [StringValidator(InvalidCharacters = "  ~!@#$%^&*()[]{}/;’\"|\\")]
        public string Username
        {
            get { return (string)this["username"]; }
            set { this["username"] = value; }
        }

        [ConfigurationProperty("SSHport", IsRequired = true, DefaultValue = 22)]
        [IntegerValidator(MinValue = 1, MaxValue = 65536)]
        public int SSHPort
        {
            get { return (int)this["SSHport"]; }
            set { this["SSHport"] = value; }
        }
 
        [ConfigurationProperty("password", IsRequired = false)]
        public string Password
        {
            get { return (string)this["password"]; }
            set { this["password"] = value; }
        }
 
        [ConfigurationProperty("privatekey", IsRequired = false)]
        public string Privatekey
        {
            get { return (string)this["privatekey"]; }
            set { this["privatekey"] = value; }
        }
 
        [ConfigurationProperty("privatekeypassphrase", IsRequired = false)]
        public string Privatekeypassphrase
        {
            get { return (string)this["privatekeypassphrase"]; }
            set { this["privatekeypassphrase"] = value; }
        }
 
        [ConfigurationProperty("tunnels", IsDefaultCollection = false)]
        public TunnelCollection Tunnels
        {
            get { return (TunnelCollection)base["tunnels"]; }
        }
    }
 
    public class TunnelCollection : ConfigurationElementCollection
    {
        public new TunnelConfigElement this[string name]
        {
            get
            {
                if (IndexOf(name) < 0) return null;
                return (TunnelConfigElement)BaseGet(name);
            }
        }
 
        public TunnelConfigElement this[int index]
        {
            get { return (TunnelConfigElement)BaseGet(index); }
        }
 
        public int IndexOf(string name)
        {
            name = name.ToLower();
 
            for (int idx = 0; idx < base.Count; idx++)
            {
                if (this[idx].Name.ToLower() == name)
                    return idx;
            }
            return -1;
        }
 
        public override ConfigurationElementCollectionType CollectionType
        {
            get { return ConfigurationElementCollectionType.BasicMap; }
        }
 
        protected override ConfigurationElement CreateNewElement()
        {
            return new TunnelConfigElement();
        }
 
        protected override object GetElementKey(ConfigurationElement element)
        {
            return ((TunnelConfigElement)element).Name;
        }
 
        protected override string ElementName
        {
            get { return "tunnel"; }
        }
    }
 
    public class TunnelConfigElement : ConfigurationElement
    {        
        public TunnelConfigElement()
        {
        }
 
        public TunnelConfigElement(string name, int localport, int remoteport, string destinationserver)
        {
            this.DestinationServer = destinationserver;
            this.RemotePort = remoteport;
            this.LocalPort = localport;            
            this.Name = name;
        }
 
        [ConfigurationProperty("name", IsRequired = true, IsKey = true, DefaultValue = "")]       
        public string Name
        {
            get { return (string)this["name"]; }
            set { this["name"] = value; }
        }        
 
        [ConfigurationProperty("localport", IsRequired = true, DefaultValue =1)]
        [IntegerValidator(MinValue = 1, MaxValue = 65536)]
        public int LocalPort
        {
            get { return (int)this["localport"]; }
            set { this["localport"] = value; }
        }
 
        [ConfigurationProperty("remoteport", IsRequired = true, DefaultValue =1)]
        [IntegerValidator(MinValue = 1, MaxValue = 65536)]
        public int RemotePort
        {
            get { return (int)this["remoteport"]; }
            set { this["remoteport"] = value; }
        }
 
        [ConfigurationProperty("destinationserver", IsRequired = true)]
        [StringValidator(InvalidCharacters = "  ~!@#$%^&*()[]{}/;’\"|\\")]
        public string DestinationServer
        {
            get { return (string)this["destinationserver"]; }
            set { this["destinationserver"] = value; }
        }
    }
}

And the configuration code

 <?xml version="1.0"?>
 <configuration>
   <configSections>
     <section name="TunnelSection" type="SSHTunnelWF.TunnelSection,SSHTunnelWF" />
   </configSections>
   <TunnelSection>
     <host SSHServerHostname="tsg.edssdn.net" username="user" SSHport="22" password="pass" privatekey="" privatekeypassphrase="">
       <tunnels>
         <tunnel name="tfs" localport="8081"  remoteport="8080" destinationserver="tfs2010.dev.com"  />
         <tunnel name="sql" localport="14331"  remoteport="1433" destinationserver="sql2008.dev.com"  />
         <tunnel name="crm2011app" localport="81"  remoteport="80" destinationserver="crm2011betaapp.dev.com"  />
       </tunnels>
     </host>
     <host SSHServerHostname="blade16" username="root" SSHport="22"  password="pass" privatekey="" privatekeypassphrase="">
      <tunnels>
        <tunnel name="vnc" localport="5902"  remoteport="5902" destinationserver="blade1.dev.com" />
      </tunnels>
     </host>
   </TunnelSection>
 </configuration>

And then the "call"

TunnelSection tunnels = ConfigurationManager.GetSection("TunnelSection") as TunnelSection