如何使用 Newtonsoft.Json 将对象序列化为带有类型信息的 json? [英] How to serialize object to json with type info using Newtonsoft.Json?

问题描述

当我序列化某些类型的对象时，我希望在 JSON 中有一个类型名称为类型的属性.我写了一个转换器:

I want to have a property with type name in JSON when I serialize objects of certain types. I wrote a converter:

public class TypeInfoConverter : JsonConverter {
    private readonly IEnumerable<Type> _types;

    public TypeInfoConverter(IEnumerable<Type> types) {
        Contract.Requires(types != null);

        _types = types;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) {
        var jObject = JObject.FromObject(value, serializer);
        jObject.AddFirst(new JProperty("Type", value.GetType().Name));
        jObject.WriteTo(writer);
    }

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

    public override bool CanConvert(Type objectType) {
        return _types.Any(t => t.IsAssignableFrom(objectType));
    }
}

但是当我尝试序列化对象时，我在这里有一个无限递归:var jObject = JObject.FromObject(value, serializer); 这很明显，因为我使用了与该转换器配置的相同 JsonSerializer 实例.

But when I'm trying to serialize object I have an infinity recursion here: var jObject = JObject.FromObject(value, serializer); It is obvious because I use the same instance of JsonSerializer which was configured with that converter.

如何防止使用这个转换器，但是我想使用为这个序列化器配置的其他转换器?

How to prevent using this converter, but I want to use other converters which configured for this serializer?

我要序列化的类型:

public interface ITaskResult {
}

public class UserHasRejectedOffer : ITaskResult {
    public string Message { get; set; }
}

public class UserHasFilledForm : ITaskResult {
    public string FormValue1 { get; set; }

    public string Formvalue2 { get; set; }
}

...

推荐答案

public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) 
    var converters = serializer.Converters.Where(x => !(x is TypeInfoConverter)).ToArray();

    var jObject = JObject.FromObject(value);
    jObject.AddFirst(new JProperty("Type", value.GetType().Name));
    jObject.WriteTo(writer, converters);
}

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