Question

I’m trying to implement a dictionary for use with WCF. My requirements are:

• actual (private variable or base class) type equivalent to Dictionary
• Comparer = System.StringComparer.InvariantCultureIgnoreCase
• Custom (override/new) Add(key, value) method (to include validations).
• Override ToString()
• Use of the same type on both the client and host

I’ve attempted using this class in a common project shared by the WCF host and client projects:

[Serializable] public class MyDictionary : Dictionary<string, object> {   public MyDictionary()     : base(System.StringComparer.InvariantCultureIgnoreCase)   { }    public new void Add(string key, object value)   { /* blah */ }    public override string ToString()   { /* blah */ } }  [DataContract] [KnownType(typeof(MyDictionary))] [KnownType(typeof(object[]))] [KnownType(typeof(double[]))] [KnownType(typeof(string[]))] [KnownType(typeof(DateTime[]))] public class ResultClass {   public object Value{ get; set; }   /* More properties */ } public class ParmData {   public object Value{ get; set; }   /* More properties */ } [DataContract] [KnownType(typeof(MyDictionary))] [KnownType(typeof(object[]))] [KnownType(typeof(double[]))] [KnownType(typeof(string[]))] [KnownType(typeof(DateTime[]))] public class ParameterClass {   public List<ParmData> Data{ get; set; }   /* More properties */ }  [OperationContract] ResultClass DoSomething(ParameterClass args); 

Results:

• When I pass MyDictionary as one of the ParameterClass.Data.Value elements, I get a missing KnownType exception.
• I can safely return MyDictionary in the ResultClass, but it is no longer my type. It is just a Dictionary, and is not castable to MyDictionary. Also comparer = System.Collections.Generic.GenericEqualityComparer<string>, not the case insensitive comparer I’m looking for.

The help I’m asking for is to either fix my failed attempt, or a completely different way to achieve my stated requirements. Any solution should not involve copying one dictionary to another.

Thanks

Answer 1

• Use the CollectionDataContract attribute as jezell suggested
• Manually generate the reference (proxy) code with SvcUtil, using the /collectionType parameter. This parameter is not supported by the vs2008 service reference GUI.

Source: WCF Collection Type Sharing