ProtoBuf-Net 错误：没有为内部 class 类型定义序列化程序

Question

When using protobuf-net, I have a class Data decorated with [ProtoContract] attribute, which defines an inner class. Members of that type should be serialized as well.

[ProtoContract] 
public class Data {
    [ProtoMember(1)]
    public string Member { get; set; }
    
    [ProtoMember(2)]
    public NestedData Nested { get; set; }

    public class NestedData
    {
        [ProtoMember(1)]
        public string InnerMember { get; set; }
    } 
}

When I instantiate this class and try to serialize it using ProtoBuf.Serializer.Serialize(System:IO.Stream, Data) , this raises an exception "System.InvalidOperationException: 'No serializer defined for type: MinimalExample.Data+NestedData'". I guess that I just have a blind spot - where is my error? I would be rather surprised if protobuf-net had a problem with handling inner classes in general.

I am using protobuf-net 3.0.101 on .net 5.

Answer 1

You just need to annotate NestedData with [ProtoContract] :

[ProtoContract]
public class Data
{
    [ProtoMember(1)]
    public string Member { get; set; }

    [ProtoMember(2)]
    public NestedData Nested { get; set; }

    [ProtoContract]
    public class NestedData
    {
        [ProtoMember(1)]
        public string InnerMember { get; set; }
    }
}

Test:

void Main()
{
    var data = new Data
    {
        Member = "member",
        Nested = new Data.NestedData
        {
            InnerMember = "inner"
        }
    };


    using var mem = new MemoryStream();
    ProtoBuf.Serializer.Serialize(mem, data);
    mem.Position = 0;

    var data2 = ProtoBuf.Serializer.Deserialize<Data>(mem);
}