public class Entity
    {
        [JsonConverter(typeof(EntityIdJsonConverter))]//这个有没有效果都一样
        public EntityId Id { get; set; }
    }

    [JsonConverter(typeof(EntityIdJsonConverter))]
    public struct EntityId
    {
        public Guid Id { get; set; }

        public override string ToString()
        {
            return this.Id.ToString();
        }

        public static implicit operator Guid(EntityId objId) => objId.Id;

        public static implicit operator EntityId(Guid objId) => new EntityId { Id = objId };

        public static implicit operator string(EntityId objId) => objId.Id.ToString();

        public static implicit operator EntityId(string objId) => new EntityId { Id = Guid.Parse(objId) };
    }

    internal sealed class EntityIdJsonConverter : JsonConverter
    {
        public override bool CanConvert(Type objectType)
        {
            return true;
        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            string value = reader.ReadAsString();
            Expression exp = Expression.Constant(value);
            exp = Expression.Convert(exp, objectType);
            var l = Expression.Lambda(exp);
            return l.Compile().DynamicInvoke();
        }

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

var entity = new Entity{Id = Guid.NewGuid()};
var json = JsonConvert.SerializeObject(entity);
//触发了转换器的函数 WriteJson
//结果 ： { "Id":"guid字符串"}，正确，满足我需要
var entity2 = JsonConvert.DeserializeObject<Entity>(json);
//报告错误，未触发 转换器函数  ReadJson