动态linq，实现查询动态字段

        /// <summary>
        /// 综保电量统计
        /// </summary>
        /// <param name="mod">时间维度：Y年、M月、D日、T时间段</param>
        /// <param name="time">时间</param>
        /// <returns>该时间内各回路电量使用情况</returns>
        public async Task<dynamic> GetRealyEnergyStat(string mod, DateTime time)
        {
            using (PDMDBContext db = new PDMDBContext())
            {
                var realyList = db.RelayDevice.Select(m => new { m.Name, m.ID }).Distinct().ToList();

                var queryWhere = db.RealyDayEnergyStat
                                .Where(m => mod == "Y" ? m.RcdTime.Year == time.Year :
                                            mod == "M" ? m.RcdTime.ToString("yyyy/MM") == time.ToString("yyyy/MM") :
                                            mod == "D" ? m.RcdTime.ToString("yyyy/MM/dd") == time.ToString("yyyy/MM/dd") :
                                            true);

                var query = from r in queryWhere
                            group r by new
                            {
                                RcdTime = mod == "Y" ? r.RcdTime.ToString("yyyy/MM") :
                                          mod == "M" ? r.RcdTime.ToString("yyyy/MM/dd") :
                                          mod == "D" ? r.RcdTime.ToString("yyyy/MM/dd HH") :
                                          r.RcdTime.ToString("yyyy/MM/dd HH:mm:ss")
                            } into g
                            select g;

                StringBuilder param = new StringBuilder();
                foreach (var item in realyList)
                {
                    param.Append($", Where(RelayDevIDFK == {item.ID}).Sum(Wp) AS Wp{item.ID}");
                }

                var result = await query.Select($"new (Key.RcdTime {param.ToString()})").ToDynamicListAsync();

                var resultSum = await queryWhere.GroupBy(m => m.RcdTime != null).Select($"new ({param.ToString().TrimStart(',')})").ToDynamicListAsync();

                return new { realyList, result, resultSum };
            }
        }

需要引入System.Linq.Dynamic.Core