"An item with the same key has already been added" error with protobuf-net

Question

I am trying to replace an existing serializer with protobuf for C # by Mark Gravell. My code is extensive and my goal is to make it with minimal modifications.

I ran into a problem that, it seems to me, I understand why this is happening, but it needs help in overcoming - in particular, a solution that will require minimal changes to my existing code and classes. My code is complex, so I created the following short example to demonstrate the problem:

using System;
using System.Collections.Generic;
using System.IO;
using ProtoBuf;


namespace ConsoleApplication1
{
    class program_issue
    {

    [ProtoContract]
    public class Father
    {
        public Father()
        {
            sonny = new Son();
        }

        [ProtoMember(101)]
        public string Name;

        [ProtoMember(102)]
        public Son sonny;

    }

    [ProtoContract]
    public class Son
    {
        public Son()
        {
            Dict.Add(10, "ten");
        }

        [ProtoMember(103)]
        public Dictionary<int, string> Dict = new Dictionary<int, string>();
    }


    static void Main(string[] args)
    {
        Father f1 = new Father();
        f1.Name = "Hello";
        byte[] bts = PBSerializer.Serialize(typeof(Father), f1);

        Father f2;
        PBSerializer.Deserialize(bts, out f2);

    }


    public static class PBSerializer
    {
        public static byte[] Serialize(Type objType, object obj)
        {
            MemoryStream stream = new MemoryStream();
            ProtoBuf.Serializer.Serialize(stream, obj);
            string s = Convert.ToBase64String(stream.ToArray());
            byte[] bytes = stream.ToArray();
            return bytes;
        }


        public static void Deserialize(byte[] data, out Father obj)
        {
            using (MemoryStream stream = new MemoryStream(data))
            {
                obj = ProtoBuf.Serializer.Deserialize<Father>(stream);
            }

        }
    }

}
}

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?

, .

Answer 1

:

[ProtoContract(SkipConstructor = true)]

, , ( ). , , null, . ( ):

[ProtoBeforeDeserialization]
private void Foo()
{
    Dict.Clear();
}

:

[ProtoContract(SkipConstructor = true)]

[ProtoAfterDeserialization]
private void Foo()
{
    if(Dict == null) Dict = new Dictionary<int,string>();
}

, . , Father, Son .