C# Json.Deserialize with Object with Child class with interfaces

Question

我有一些对象:

public class MyObject
{
    public MyField Field { get; set; }
}

public class MyField
{
    [JsonProperty]
    public Entity MyEntity { get; set; }
    public IEntity IMyEntity { get; set; }
}

public interface IEntity
{
    string MyStr { get; }
}

public class Entity : IEntity
{
}

然后我尝试做类似的事情

JsonConvert.DeserializeObject<MyObject>(myObjStr); 

抛出类似的错误

Could not create an instance of type MyObject... Type is an interface or abstract class and cannot be instantiated. Path 'MyField.IMyEntity.MyInt'

我无法更改字段或实体，因为它在另一个组的代码库中。 MyObject 类在我的。有没有办法反序列化这个对象？我在这里尝试了一些使用 JsonSerializerSettings 的东西 JSON.NET - how to deserialize collection of interface-instances?但无济于事。

Answer 1

您可以创建自己的 JSON 转换器，它允许您指定类型映射:

public class JsonTypeMapper<TFromType, TToType> : JsonConverter
{
    public override bool CanConvert(Type objectType) => objectType == typeof(TFromType);

    public override object ReadJson(JsonReader reader,
     Type objectType, object existingValue, JsonSerializer serializer)
    {
        return serializer.Deserialize<TToType>(reader);
    }

    public override void WriteJson(JsonWriter writer,
        object value, JsonSerializer serializer)
    {
        serializer.Serialize(writer, value);
    }
}

然后你像这样反序列化:

JsonConvert.DeserializeObject<MyObject>(myObjStr, new JsonSerializerSettings
{
    Converters = new List<JsonConverter> { new JsonTypeMapper<IEntity, Entity>() }
                                                            //^^^^^^^, ^^^^^^
});