c# - 无法使用接口(interface)反序列化类型

Question

下面的代码片段尝试使用它的接口(interface)序列化一个项目并反序列化。 请解释一下如何反序列化从接口(interface)继承的类型，如示例

class Program
{
 static void Main()
 {
 Item item = new Item { A = 123321 };

 using (MemoryStream ms = new MemoryStream())
 {
 Serializer.Serialize(ms  item);
 ms.Position = 0;
 Serializer.Deserialize<IItem>(ms);
 }
 }
}


ProtoInclude(100  typeof(Item))
public interface IItem
{
 int A { get; set; }
}

public class Item : IItem
{
 ProtoMember(1)
 public int A { get; set; }
}

提出错误:

The type can't be Updated once a serializer has been produced for test.Item >(test.IItem)
at ProtoBuf.Meta.RuntimeTypeModel.GetKey(Type type  Boolean demand  Boolean getBaseKey) in C:\Dev\protobuf-net\protobuf-net\Meta\RuntimeTypeModel.cs:line 388
at ProtoBuf.Meta.RuntimeTypeModel.GetKeyImpl(Type type) in C:\Dev\protobuf-net\protobuf-net\Meta\RuntimeTypeModel.cs:line 362
at ProtoBuf.Meta.TypeModel.GetKey(Type& type) in C:\Dev\protobuf-net\protobuf-net\Meta\TypeModel.cs:line 982
at ProtoBuf.Meta.TypeModel.DeserializeCore(ProtoReader reader  Type type  Object value  Boolean noAutoCreate) in C:\Dev\protobuf-net\protobuf-net\Meta\TypeModel.cs:line 576
at ProtoBuf.Meta.TypeModel.Deserialize(Stream source  Object value  Type type  SerializationContext context) in C:\Dev\protobuf-net\protobuf-net\Meta\TypeModel.cs:line 506
at ProtoBuf.Meta.TypeModel.Deserialize(Stream source  Object value  Type type) in C:\Dev\protobuf-net\protobuf-net\Meta\TypeModel.cs:line 488
at ProtoBuf.Serializer.DeserializeT(Stream source) in C:\Dev\protobuf-net\protobuf-net\Serializer.cs:line 69
at test.Program.Main() in ...

Answer 1

基本上，目前，接口(interface)支持适用于属性/列表等，但不适用于根对象。所以你需要一个具体的根类型。除此之外 - 基本上就在那里 - 我将 ProtoMember(1) 移至界面，这感觉更自然 - 但是:

using System.IO;
using ProtoBuf;

class Program
{
    static void Main()
    {
        Item item = new Item { A = 123321 }; 

        var obj = new Wrapper { Item = item };
        using (MemoryStream ms = new MemoryStream())
        {
            Serializer.Serialize(ms, obj);
            ms.Position = 0;
            IItem iObj = Serializer.Deserialize<Wrapper>(ms).Item;
            Item cObj = (Item)iObj;
        }
    }
}

[ProtoContract]
class Wrapper
{
    [ProtoMember(1)]
    public IItem Item { get;set; }
}

[ProtoContract]
[ProtoInclude(2, typeof(Item))]
public interface IItem
{
    [ProtoMember(1)]
    int A { get; set; }
}

[ProtoContract]
public class Item : IItem
{
    public int A { get; set; }
}