StringWriter sw = new StringWriter(CultureInfo.InvariantCulture);
        JsonSerializer jsonSerializer = new JsonSerializer();
        jsonSerializer.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
        using (JsonWriter jsonWriter = new JsonTextWriter(sw))
        {
            jsonWriter.Formatting = Formatting.Indented;
            jsonSerializer.Serialize(jsonWriter, value);
        }
        return sw.ToString();

另外,会出现集合被更改的错误,是需要把nhibernate的配置文件增加lazy=false即可；