Json.net反序列化接口，具体类使用JsonConverter

Question

我的问题是，当转换器应用于接口的实现时，我的JsonConverter似乎不会被json.net反序列化过程调用，而属性类型是接口。我使用TypeNameHandling=TypeNameHanding。对象将$type添加到json中。我在序列化和反序列化时都这样做。当我有一个接口实现的属性时，类转换器就会被正确调用。但是，当我有一个接口类型的属性时，不会调用具体类的converter。

当我反序列化这个类时，我的JsonDataBagCreationConverter将被RealTelephone调用，但不会被Telephone调用。因为这是一个接口。即使它们都是用正确的$类型序列化的。这导致RealTelephone拥有它的。数据已填充，而电话。数据为null。

[JsonConverter(typeof(JsonDataBagCreationConverter<ContainerForITelephone>))]
public class ContainerForITelephone : IDataBag
{
private object _data;
private DataBagTypeEnum _dataBagTypeEnum;
public ITelephone Telephone { get; set; }
public Telephone RealTelephone { get; set; }
public object Data
{
get { return _data; }
set { _data = value; }
}
public DataBagTypeEnum DataBagType_Enum
{
get { return _dataBagTypeEnum; }
}
}

没有为Telephone属性调用此jsonconverter。但它适用于RealTelephone。

public class JsonDataBagCreationConverter<T> : JsonConverter where T : IDataBag, new()
{       
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{           
if (reader.TokenType != JsonToken.Null) 
{
var jsonObject = JObject.Load(reader);
var target = Create(objectType, jsonObject);
serializer.Populate(jsonObject.CreateReader(), target); 
((IDataBag)target).Data = jsonObject.ToString(); 
return target;
}
return null;
}

}

[JsonConverter(typeof(JsonDataBagCreationConverter<Telephone>))]
public class Telephone : ITelephone
{
public string Name { get; set; }
public string AreaCode { get; set; }
public string Number { get; set; }
public SubPhone SubPhone { get; set; }
public object Data { get; set; }
public DataBagTypeEnum DataBagType_Enum { get; set; }
}

我期待着收到你的来信，谢谢

1月

Answer 1

已解决：

public class JsonDataBagCreationConverter<T> : JsonConverter where T:IDataBag 
{
//, new() prevented us from using interfaces. Activator.CreateInstance did the trick in Create
//Used when the object decorated with  [JsonConverter(typeof(JsonDataBagCreationConverter<xxxx>))] is de-serialized
public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
{
var  jsonObject = JObject.Load(reader);
if (objectType.IsInterface)
{
// Interfaces cannot be instantiated but must be converted to their "real" implemented type
// Because we serialize with settings.TypeNameHandling = TypeNameHandling.Objects; 
// A $type property is added to the json by the deserializer.
string type = jsonObject["$type"].ToString();
var typesAsArray = type.Split(',');
var wrappedTarget = Activator.CreateInstance(typesAsArray[1], typesAsArray[0]);
var realTarget = wrappedTarget.Unwrap() as IDataBag; 
serializer.Populate(jsonObject.CreateReader(), realTarget); // Will call this function recursively for any objects that have JsonDataBagCreationConverter as attribute
((IDataBag)realTarget).Data = jsonObject.ToString(); // This is where custom data is stored in databag
return realTarget; 
}
// Non interface
var target = Create(objectType, jsonObject);
serializer.Populate(jsonObject.CreateReader(), target); // Will call this function recursively for any objects that have JsonDataBagCreationConverter as attribute
((IDataBag)target).Data = jsonObject.ToString(); // This is where custom data is stored in databag
return target;

}
public override bool CanRead
{
get
{
return true; 
}
}
public override bool CanWrite
{
get
{
return false; 
}
}
public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
{
throw new Exception("WriteJson not implemented");
}
protected IDataBag Create(Type objectType, JObject jsonObject)
{
var aa = Activator.CreateInstance(objectType);
return aa as IDataBag;
// return new T(); // this demands ,new() on the class and then it will not work with interfaces
}
public override bool CanConvert(Type objectType)
{
return typeof(T).IsAssignableFrom(objectType);
}

}