I have a WinForms fat client application backed by a ASP.NET WebService. I would like to do my data access with NHibernate in the web service. However, when I try to serialize my domain object through the web service, I get the exception:

"You must implement a default accessor on Iesi.Collections.ISet because it inherits from ICollection."

I believe I'm using NHibernate correctly. My application works when I run it all in one process (directly call the object loading code without a web service wrapper). I recognize that ISet doesn't declare the default indexer (object this[object key] { get; set; }) because it is trying to provide set semantics. However, I believe that this accessor should be added to ISet to support serialization.

Does this sound correct? Is there anything I'm doing wrong? I've included the stack trace below for reference.

Aaron

[InvalidOperationException: You must implement a default accessor on Iesi.Collections.ISet because it inherits from ICollection.]
System.Xml.Serialization.TypeScope.GetCollectionElementType(Type type) +580
System.Xml.Serialization.TypeScope.ImportTypeDesc(Type type, Boolean canBePrimitive, MemberInfo memberInfo) +549
System.Xml.Serialization.TypeScope.GetTypeDesc(Type type, MemberInfo source, Boolean directReference) +50
System.Xml.Serialization.StructModel.GetPropertyModel(PropertyInfo propertyInfo) +57
System.Xml.Serialization.StructModel.GetFieldModel(MemberInfo memberInfo) +88
System.Xml.Serialization.XmlReflectionImporter.ImportStructLikeMapping(StructModel model, String ns) +1532
System.Xml.Serialization.XmlReflectionImporter.ImportTypeMapping(TypeModel model, String ns, ImportContext context, String dataType, Boolean repeats) +440

I just cheated.

I did

I did much the same and I think that is a good solution.

However, for some situations I am using classes that I cannot change. I have tried things like extending the class, overriding the property and adding XMLIgnore on the overridden one, but that doesn't seem to work. I still get the same error message.

In those cases you might have to break down and implement IXMLSerializable and serialize the properties which are classes you can't change manually. Quite tedious, but doable.