Protobuf attributes with a hierarchy of generic classes

Question

I have a class hierarchy that looks like this. These classes contain a lot of other details which I have excluded. This is a simplification to focus on the serialization a

Answer 1

OK; with the updated question I understand a bit more. I expect the generics in the middle of the object-model are indeed going to make life... "fun". It doesn't work "out of the box"; I looked to see if there were some simple tweaks I could make to support it, but it started getting ugly pretty quickly. I expect it would be better to simply remove the need for the generic in the middle, if possible - perhaps retaining a generic interface (rather than the generic class). Here's some code that does work; how this maps to your code... I can't tell 100%. Note you don't have to use the TypeDescriptor stuff (etc) - it just seemed that since you are using code-gen this might make some things easier...

(I didn't check the DataSet stuff - just the class stuff)

using System;
using System.ComponentModel;
using System.Data;
using System.IO;
using NUnit.Framework;
using ProtoBuf;

[TestFixture]
public class ComplexGenericTest
{
    [Test]
    public void TestX()
    {
        Query query = new X { Result = "abc" };
        Assert.AreEqual(typeof(string), query.GetQueryType());
        Query clone = Serializer.DeepClone(query);
        Assert.IsNotNull(clone);
        Assert.AreNotSame(clone, query);
        Assert.IsInstanceOfType(query.GetType(), clone);
        Assert.AreEqual(((X)query).Result, ((X)clone).Result);
    }
    [Test]
    public void TestY()
    {
        Query query = new Y { Result = 1234};
        Assert.AreEqual(typeof(int), query.GetQueryType());
        Query clone = Serializer.DeepClone(query);
        Assert.IsNotNull(clone);
        Assert.AreNotSame(clone, query);
        Assert.IsInstanceOfType(query.GetType(), clone);
        Assert.AreEqual(((Y)query).Result, ((Y)clone).Result);
    }

}
public static class QueryExt {
    public static Type GetQueryType(this IQuery query)
    {
        if (query == null) throw new ArgumentNullException("query");
        foreach (Type type in query.GetType().GetInterfaces())
        {
            if (type.IsGenericType
                && type.GetGenericTypeDefinition() == typeof(IQuery<>))
            {
                return type.GetGenericArguments()[0];
            }
        }
        throw new ArgumentException("No typed query implemented", "query");
    }
}
public interface IQuery
{
    string Result { get; set; }
}
public interface IQuery : IQuery
{
    new T Result { get; set; }
}

[ProtoInclude(21, typeof(W))]
[ProtoInclude(22, typeof(X))]
[ProtoInclude(23, typeof(Y))]
[ProtoInclude(25, typeof(SpecialQuery))]
[ProtoContract]
abstract class Query : IQuery
{
    public string Result
    {
        get { return ResultString; }
        set { ResultString = value; }
    }
    protected abstract string ResultString { get; set; }

    // these are to allow simple ResultString implementations
    // without the codegen having to worry about int.Parse etc
    protected static string FormatQueryString(T value)
    {
        return TypeDescriptor.GetConverter(typeof(T))
            .ConvertToInvariantString(value);
    }
    protected static T ParseQueryString(string value)
    {
        return (T) TypeDescriptor.GetConverter(typeof(T))
            .ConvertFromInvariantString(value);
    }
}
[ProtoContract]
[ProtoInclude(21, typeof(Z))]
abstract class SpecialQuery : Query, IQuery
{

    public new DataSet Result { get; set; }

    [ProtoMember(1)]
    protected override string ResultString
    {
        get {
            if (Result == null) return null;
            using (StringWriter sw = new StringWriter())
            {
                Result.WriteXml(sw, XmlWriteMode.WriteSchema);
                return sw.ToString();
            }
        }
        set {
            if (value == null) { Result = null; return; }
            using (StringReader sr = new StringReader(value))
            {
                DataSet ds = new DataSet();
                ds.ReadXml(sr, XmlReadMode.ReadSchema);
            }
        }
    }
}

[ProtoContract]
class W : Query, IQuery
{
    [ProtoMember(1)]
    public new bool Result { get; set; }

    protected override string ResultString
    {
        get {return FormatQueryString(Result); }
        set { Result = ParseQueryString(value); }
    }
}
[ProtoContract]
class X : Query, IQuery
{
    [ProtoMember(1)]
    public new string Result { get; set; }

    protected override string ResultString
    {
        get { return Result ; }
        set { Result = value; }
    }
}
[ProtoContract]
class Y : Query, IQuery
{
    [ProtoMember(1)]
    public new int Result { get; set; }

    protected override string ResultString
    {
        get { return FormatQueryString(Result); }
        set { Result = ParseQueryString(value); }
    }
}
[ProtoContract]
class Z : SpecialQuery
{
}