利用linq实现日统计

场景描述：

用户在每天都有会N条记录，现在要实现每天有个统计信息，相当外层显示日统计信息，第二层显示每日明细数据。

代码如下：

        /// <summary>
        /// 30天内用户的**统计及日明细
        /// </summary>
        /// <param name="userId"></param>
        /// <returns></returns>
        public static List<DtoSitDayCountInfo> ListSitInfoFor30Days(int userId)
        {
            var listResut = new List<DtoSitDayCountInfo>();
            try
            {
                var list = SitInMeditationDal.ListSitInfoFor30Days(userId);
                if(list!=null)
                {
                    var groupDay = from listday in list
                                   group listday by new { curDate = listday.EndTime.ToShortDateString() } into g
                                   select new DtoSitDayCountInfo
                                   {
                                       CurDate = g.Key.curDate,
                                       TotalDuration = g.Sum(p => p.Duration),
                                       TotalTimes = g.Count(),
                                       MaxDuration = g.Max(p=>p.Duration),
                                       AvgDuration = g.Average(p=>p.Duration).ToInt32(),
                                   };
                    if (groupDay != null)
                    {
                        listResut = groupDay.ToList();

                        foreach (var item in listResut)
                        {
                            item.ListDay = list.FindAll(p => p.EndTime.ToShortDateString() == item.CurDate); 
                        }
                    }
                }
            }
            catch (Exception e)
            {
                Log.Error(e.Message + e.StackTrace);
            }
            return listResut;
        }

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