在实体框架查询中使用带有标志的枚举 [英] Using a enum with flag in an Entity Framework query

问题描述

我的枚举类型如下

  [Flags]
    public enum WeekDays
    {

        Monday = 1,
        Tuesday = 2,
        Wednesday = 4,
        Thursday = 8,
        Friday = 16,
        Saturday = 32,
        Sunday = 64,
    }


   WeekDays dw = WeekDays.Friday | WeekDays.Monday | WeekDays.Saturday;

   int dwInt = (int)dw;

   var list = query.Where(f => f.FromDateTime.DayOfWeek == dwInt "??????????? what can i do there????").ToList();

推荐答案

解决方案在这里

 public static Dictionary<int, int> map = new Dictionary<int, int>() { { 0, 64 }, { 1, 1 }, { 2, 2 }, { 3, 4 }, { 4, 8 }, { 5, 16 }, { 6, 32 } };

//actually,this gets from a user interface,but we shoul be focus database layer
WeekDays[] dw = new WeekDays[] {WeekDays.Saturday,WeekDays.Tuesday,WeekDays.Wednesday };

int[] systemDayOfWeekList = new int[daysOfWeek.Length];

for (int i = 0; i < daysOfWeek.Length; i++)
{
  systemDayOfWeekList[i] = map.FirstOrDefault(e => e.Value == (int)daysOfWeek[i]).Key;
}

query = query.Where(f => dayOfWeekList.Contains(((int)SqlFunctions.DatePart("dw", f.FromDateTime))));

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