JSON.Net 在使用 [JsonConvert()] 时抛出 StackOverflowException

我编写了这个简单的代码来将类序列化为扁平化，但是当我使用[JsonConverter(typeof(FJson))]注释，它会抛出一个堆栈溢出异常。如果我打电话给SerializeObject手动，效果很好。

如何在注释模式下使用 JsonConvert：

class Program
    {
        static void Main(string[] args)
        {
            A a = new A();
            a.id = 1;
            a.b.name = "value";

            string json = null;

            // json = JsonConvert.SerializeObject(a, new FJson()); without [JsonConverter(typeof(FJson))] annotation workd fine
            // json = JsonConvert.SerializeObject(a); StackOverflowException

            Console.WriteLine(json);
            Console.ReadLine();
        }
    }

    //[JsonConverter(typeof(FJson))] StackOverflowException
    public class A
    {
        public A()
        {
            this.b = new B();
        }

        public int id { get; set; }
        public string name { get; set; }
        public B b { get; set; }
    }

    public class B
    {
        public string name { get; set; }
    }

    public class FJson : JsonConverter
    {
        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            JToken t = JToken.FromObject(value);
            if (t.Type != JTokenType.Object)
            {
                t.WriteTo(writer);
                return;
            }

            JObject o = (JObject)t;
            writer.WriteStartObject();
            WriteJson(writer, o);
            writer.WriteEndObject();
        }

        private void WriteJson(JsonWriter writer, JObject value)
        {
            foreach (var p in value.Properties())
            {
                if (p.Value is JObject)
                    WriteJson(writer, (JObject)p.Value);
                else
                    p.WriteTo(writer);
            }
        }

        public override object ReadJson(JsonReader reader, Type objectType,
           object existingValue, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }

        public override bool CanConvert(Type objectType)
        {
            return true; // works for any type
        }
    }

在阅读（和测试）Paul Kiar 和 p.kaneman 解决方案后，我想说这似乎是一项具有挑战性的任务来实施WriteJson。尽管它适用于大多数情况，但仍有一些边缘情况尚未涵盖。 例子：

• public bool ShouldSerialize*() methods
• null values
• 值类型（struct)
• json 转换器属性
• ..

这是（只是）另一个尝试：

public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) {
    if (ReferenceEquals(value, null)) {
        writer.WriteNull();
        return;
    }

    var contract = (JsonObjectContract)serializer
        .ContractResolver
        .ResolveContract(value.GetType());

    writer.WriteStartObject();

    foreach (var property in contract.Properties) {
        if (property.Ignored) continue;
        if (!ShouldSerialize(property, value)) continue;

        var property_name = property.PropertyName;
        var property_value = property.ValueProvider.GetValue(value);

        writer.WritePropertyName(property_name);
        if (property.Converter != null && property.Converter.CanWrite) {
            property.Converter.WriteJson(writer, property_value, serializer);
        } else {
            serializer.Serialize(writer, property_value);
        }
    }

    writer.WriteEndObject();
}

private static bool ShouldSerialize(JsonProperty property, object instance) {
    return property.ShouldSerialize == null 
        || property.ShouldSerialize(instance);
}