Linq的時間篩選
//寫法一:正常 IEnumerable<x> xList = dbContext.xs.OrderByDescending(u => u.CreateTime).Where(u => EntityFunctions.DiffDays(u.CreateTime, DateTime.Now) == 0); //寫法二:錯誤 IEnumerable<x> xList = dbContext.xs.OrderByDescending(u => u.CreateTime); xList = xList.Where(u => EntityFunctions.DiffDays(u.CreateTime, DateTime.Now) == 0); 寫法二中,在使用EntityFunctions的時候,xList對象已經是Ienumerable的類型了,是無法使用linq自帶的EntityFunctions方法的,所以會報錯,具體意思就是不識別這個方法
List的時間篩選,這里有一點是DateTime中的Date是表示日期,例如今天2017/10/17 9:45.0,Date處理后的結果就是 2017/10/17 0:00:0
#region List獲取 List<TestObj> list = new List<TestObj>(); for (int i = 0; i < 4; i++) { TestObj temp = new TestObj() { ID = i, CreateTime = DateTime.Now.AddYears(-i).AddDays(i) }; list.Add(temp); } Console.WriteLine( SerializationHelper.JsonSerialize(list.Where(u => DateTime.Compare(u.CreateTime.Date, DateTime.Now.AddYears(-1).AddDays(1).Date) == 0).ToList())); Console.WriteLine( DateTime.Now.Date); #endregion