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Help needed for the most trivial example of protobuf-net 2

Observe the following code (taken from this question ):

  [ProtoContract]
  public class B
  {
    [ProtoMember(1)] public int Y;
  }

  [ProtoContract]
  public class C
  {
    [ProtoMember(1)] public int Y;
  }

  class Program
  {
    static void Main()
    {
      object b = new B { Y = 2 };
      object c = new C { Y = 4 };
      using (var ms = new MemoryStream())
      {
        Serializer.SerializeWithLengthPrefix(ms, b, PrefixStyle.Base128);
        Serializer.SerializeWithLengthPrefix(ms, c, PrefixStyle.Base128);
        ms.Position = 0;
        var b2 = Serializer.DeserializeWithLengthPrefix<B>(ms, PrefixStyle.Base128);
        Debug.Assert(((B)b).Y == b2.Y);
        var c2 = Serializer.DeserializeWithLengthPrefix<C>(ms, PrefixStyle.Base128);
        Debug.Assert(((C)c).Y == c2.Y);
      }
    }
  }

Obviously, the wrong code, because b, and cdeclared to be object, but I is serialized using a common method Serializer.Serialize<T>:

System.ArgumentOutOfRangeException occurred
  Message=Specified argument was out of the range of valid values.
Parameter name: index
  Source=protobuf-net
  ParamName=index
  StackTrace:
       at ProtoBuf.Meta.BasicList.Node.get_Item(Int32 index)
  InnerException:

Everything works fine if I update bhow band chow c. However, I need them to be declared as object, so I assume that I need to serialize them using a non-general method Serializer.NonGeneric.SerializeWithLengthPrefix, the problem is not that I understand the meaning of the additional argument fieldNumberexpected by this method. Can someone explain what it is and how to use it here?

I am using protobuf-net v2.

Thank.

EDIT

:

RuntimeTypeModel.Default.Add(typeof(object), false).AddSubType(1, typeof(B)).AddSubType(2, typeof(C));

, , , (B = 1, C = 2), . ?

EDIT2

, :

public class GenericSerializationHelper<T> : IGenericSerializationHelper
{
  void IGenericSerializationHelper.SerializeWithLengthPrefix(Stream stream, object obj, PrefixStyle prefixStyle)
  {
    Serializer.SerializeWithLengthPrefix(stream, (T)obj, prefixStyle);
  }
}

public interface IGenericSerializationHelper
{
  void SerializeWithLengthPrefix(Stream stream, object obj, PrefixStyle prefixStyle);
}

...

static void Main()
{
  var typeMap = new Dictionary<Type, IGenericSerializationHelper>();
  typeMap[typeof(B)] = new GenericSerializationHelper<B>();
  typeMap[typeof(C)] = new GenericSerializationHelper<C>();

  object b = new B { Y = 2 };
  object c = new C { Y = 4 };
  using (var ms = new MemoryStream())
  {
    typeMap[b.GetType()].SerializeWithLengthPrefix(ms, b, PrefixStyle.Base128);
    typeMap[c.GetType()].SerializeWithLengthPrefix(ms, c, PrefixStyle.Base128);
    ms.Position = 0;
    var b2 = Serializer.DeserializeWithLengthPrefix<B>(ms, PrefixStyle.Base128);
    Debug.Assert(((B)b).Y == b2.Y);
    var c2 = Serializer.DeserializeWithLengthPrefix<C>(ms, PrefixStyle.Base128);
    Debug.Assert(((C)c).Y == c2.Y);
  }
}

, , - , . , , , .

+3
1

, , , 1 (aka Serializer.ListItemTag), , ( ).

, , API (, v2 API- - API ). TypeResolver, " ", ( ). null , , ( , , , ):

// I'm giving the example in terms of the v2 API, because there is a bug in the 
// Serializer.NonGeneric code in the beta - simply, in the first beta cut this
// doesn't correctly forward to the type-model. This will be fixed ASAP.
TypeModel model = RuntimeTypeModel.Default;
using (var ms = new MemoryStream())
{
    var tagToType = new Dictionary<int, Type>
    {  // somewhere, we need a registry of what field maps to what Type
        {1, typeof(B)}, {2, typeof(C)}
    };
    var typeToTag = tagToType.ToDictionary(pair => pair.Value, pair => pair.Key);

    object b = new B { Y = 2 };
    object c = new C { Y = 4 };
    // in v1, comparable to Serializer.NonGeneric.SerializeWithLengthPrefix(ms, b, PrefixStyle.Base128, typeToTag[b.GetType()]);
    model.SerializeWithLengthPrefix(ms, b, null, PrefixStyle.Base128, typeToTag[b.GetType()]);
    model.SerializeWithLengthPrefix(ms, c, null, PrefixStyle.Base128, typeToTag[c.GetType()]);
    ms.Position = 0;

    // in v1, comparable to Serializer.NonGeneric.TryDeserializeWithLengthPrefix(ms, PrefixStyle.Base128, key => tagToType[key], out b2);
    object b2 = model.DeserializeWithLengthPrefix(ms, null, null, PrefixStyle.Base128, 0, key => tagToType[key]);
    object c2 = model.DeserializeWithLengthPrefix(ms, null, null, PrefixStyle.Base128, 0, key => tagToType[key]);

    Assert.AreEqual(((B)b).Y, ((B)b2).Y);
    Assert.AreEqual(((C)c).Y, ((C)c2).Y);
}
+2

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