WCF Known Type from System.Object in Config

Question

I\'m trying to specify a known type in my config, but I\'m having problems with the fact that it derives from Object. I can make it work specifying the known type via attrib

Answer 1

I'm not sure if it is by design, but the KnownTypeHelper below won't throw an error if you've not declared a service contract with known types. (i.e. its optional to add known types to service contracts).

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Reflection;

/// 

/// Helper for finding the known types for Wcf Services from a configuration file.
/// 
public static class KnownTypeHelper
{
    /// 

    /// Gets the known types for the service from a configuration file.
    /// 
    /// 
    /// The provider.
    /// 
    /// 
    /// The known types for the service from a configuration file.
    /// 
    public static IEnumerable GetServiceKnownTypes(ICustomAttributeProvider provider)
    {
        var result = new List();

        var serviceKnownTypes = (ServiceKnownTypesSection)ConfigurationManager.GetSection("serviceKnownTypes");
        if (serviceKnownTypes != null)
        {
            var service = serviceKnownTypes.Services[((Type)provider).AssemblyQualifiedName];

            if (service != null)
            {
                foreach (ServiceKnownTypeElement knownType in service.KnownTypes)
                {
                    result.Add(knownType.Type);
                }
            }
        }

        return result;
    }
}

To save someone else the trouble of creating the configuration classes,

Note: There is no validation of the assembly qualified type names. If someone wants to add the appropiate attributes to do this, please do.

using System.Configuration;

/// 

/// Section for configuration known types for services.
/// 
public class ServiceKnownTypesSection : ConfigurationSection
{
    /// 

    /// Gets services.
    /// 
    [ConfigurationProperty("declaredServices", IsDefaultCollection = false)]
    [ConfigurationCollection(typeof(DeclaredServiceElement), AddItemName = "serviceContract", CollectionType = ConfigurationElementCollectionType.AddRemoveClearMap)]
    public DeclaredServiceElementCollection Services
    {
        get
        {
            return (DeclaredServiceElementCollection)base["declaredServices"];
        }
    }
}

/// 

/// Collection of declared service elements.
/// 
public class DeclaredServiceElementCollection : ConfigurationElementCollection
{
    /// 

    /// Gets the service for which known types have been declared for.
    /// 
    /// 
    /// The key of the service.
    /// 
    public new DeclaredServiceElement this[string key]
    {
        get
        {
            return (DeclaredServiceElement)BaseGet(key);
        }

        set
        {
            var element = BaseGet(key);
            var index = this.BaseIndexOf(element);
            if (BaseGet(index) != null)
            {
                BaseRemoveAt(index);
            }

            BaseAdd(index, value);
        }
    }

    /// 

    /// When overridden in a derived class, creates a new .
    /// 
    /// 
    /// A new .
    /// 
    protected override ConfigurationElement CreateNewElement()
    {
        return new DeclaredServiceElement();
    }

    /// 

    /// Gets the element key for a specified configuration element when overridden in a derived class.
    /// 
    /// 
    /// An  that acts as the key for the specified .
    /// 
    /// 
    /// The  to return the key for. 
    /// 
    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((DeclaredServiceElement)element).Type;
    }
}

/// 

/// The service for which known types are being declared for.
/// 
public class DeclaredServiceElement : ConfigurationElement
{
    /// 

    /// Gets or sets Type.
    /// 
    [ConfigurationProperty("type", IsRequired = true, IsKey = true)]
    public string Type
    {
        get
        {
            return (string) this["type"];
        }

        set
        {
            this["type"] = value;
        }
    }

    /// 

    /// Gets KnownTypes.
    /// 
    [ConfigurationProperty("knownTypes", IsDefaultCollection = false)]
    [ConfigurationCollection(typeof(DeclaredServiceElement), AddItemName = "knownType", CollectionType = ConfigurationElementCollectionType.AddRemoveClearMap)]
    public ServiceKnownTypeElementCollection KnownTypes
    {
        get
        {
            return (ServiceKnownTypeElementCollection)base["knownTypes"];
        }
    }
}

/// 

/// A collection of known type elements.
/// 
public class ServiceKnownTypeElementCollection : ConfigurationElementCollection
{
    /// 

    /// Gets an known type with the specified key.
    /// 
    /// 
    /// The key of the known type.
    /// 
    public new ServiceKnownTypeElement this[string key]
    {
        get
        {
            return (ServiceKnownTypeElement)BaseGet(key);
        }

        set
        {
            var element = BaseGet(key);
            var index = this.BaseIndexOf(element);
            if (BaseGet(index) != null)
            {
                BaseRemoveAt(index);
            }

            BaseAdd(index, value);
        }
    }

    /// 

    /// When overridden in a derived class, creates a new .
    /// 
    /// 
    /// A new .
    /// 
    protected override ConfigurationElement CreateNewElement()
    {
        return new ServiceKnownTypeElement();
    }

    /// 

    /// Gets the element key for a specified configuration element when overridden in a derived class.
    /// 
    /// 
    /// An  that acts as the key for the specified .
    /// 
    /// 
    /// The  to return the key for. 
    /// 
    protected override object GetElementKey(ConfigurationElement element)
    {
        return ((ServiceKnownTypeElement)element).Type;
    }
}

/// 

/// Configuration element for a known type to associate with a service.
/// 
public class ServiceKnownTypeElement : ConfigurationElement
{
    /// 

    /// Gets or sets TypeString.
    /// 
    [ConfigurationProperty("type", IsRequired = true, IsKey = true)]
    public string TypeString
    {
        get
        {
            return (string)this["type"];
        }

        set
        {
            this["type"] = value;
        }
    }

    /// 

    /// Gets or sets Type.
    /// 
    public Type Type
    {
        get
        {
            return Type.GetType(this.TypeString);
        }

        set
        {
            this["type"] = value.AssemblyQualifiedName;
        }
    }
}