c# - 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 aspect of these classes.

[ProtoInclude(1, typeof(Query<bool>))]
[ProtoInclude(2, typeof(Query<string>))]
[ProtoInclude(3, typeof(Query<int>))]
[ProtoInclude(4, typeof(Query<decimal>))]
[ProtoInclude(5, typeof(Query<DataSet>))]
abstract class Query
{
    public string Result { get; set; }
}
[ProtoInclude(1, typeof(SpecialQuery)]
abstract class Query<T> : Query
{
    public new T Result { get; set; }
}
abstract class SpecialQuery : Query<DataSet>
{
    public new string Result { get; set; }
}

I also have about 150 auto-generated descendants of generic Query, with a large variety of generic types. For example:

[ProtoContract]
class W : Query<bool>
{
}
[ProtoContract]
class X : Query<string>
{
}
[ProtoContract]
class Y : Query<int>
{
}
[ProtoContract]
class Z : SpecialQuery
{
}

I've also autogenerated [ProtoInclude] for all those types. For example:

[ProtoInclude(1, typeof(W)]
[ProtoInclude(2, typeof(X)]
[ProtoInclude(3, typeof(Y)]
[ProtoInclude(4, typeof(Z)]

The question is, how do I deploy those 150 ProtoIncludes? I've tried various combinations that seem logical, but I get various exceptions depending on which attributes are present where. The types that are actually need serialization in the above example would be W, X, Y, Z, only there's about 150 of them.

Can protobuf-net even deal with something like this, or should I try some other kind of serialization?

Answer 1

I'm not 100% sure I understand the scenario you want to model; however, [ProtoInclude] only looks one level of inheritance away.

If I understand correctly, try the following; note that you would need to know the potential generic types at compile time at the moment:

using System;
using ProtoBuf;
[ProtoContract]
[ProtoInclude(2, typeof(Response))]
[ProtoInclude(3, typeof(Query))]
class Packet
{
    [ProtoMember(1)]
    int ID;
}
[ProtoContract]
[ProtoInclude(1, typeof(Response<int>))]
[ProtoInclude(2, typeof(Response<decimal>))]
[ProtoInclude(3, typeof(Response<string>))]
class Response : Packet
{
}
[ProtoContract]
class Response<T> : Response
{
    [ProtoMember(2)]
    public T Value;

    public override string ToString()
    {
        return typeof(T).Name + ": " + Value;
    }
}
static class Program
{
    static void Main()
    {
        Packet packet = new Response<int> { Value = 123 };
        Packet clone = Serializer.DeepClone<Packet>(packet);
        Console.WriteLine(clone.ToString()); // should be int/123
    }
}