Newtonsoft.Json.SerializeObject 转换参数

var model_JsonSerializerSettings = new JsonSerializerSettings()
            {
                ReferenceLoopHandling = ReferenceLoopHandling.Ignore,       //
                DateFormatString = "yyyy-MM-dd HH:mm:ss"    //输出时间格式
                //其他以后补充
            };
            return JsonConvert.SerializeObject(r, Formatting.Indented, model_JsonSerializerSettings);