如何在C＃中使用謂詞來避免和或條件

Question

var queryableDcbooking = (from t in dcBookingEntities.Bookings
  join t1 in dcBookingEntities.BookingWorkFlowStatusMasters on t.BookingWorkFlowStatusId equals t1.BookingWorkFlowStatusId
  join t2 in dcBookingEntities.StatusMasters on t.StatusId equals t2.StatusId
  join t3 in dcBookingEntities.PNBStatusMasters on t.PNBStatusId equals t3.PNBStatusId into gj
  from pnb in gj.DefaultIfEmpty()
  where (
  (paraName.ToLower() == Comparator.Bookingid && intSearch.Contains(t.BookingId))
  || (paraName.ToLower() == Comparator.Dccode && strSearch.Contains(t.DCMaster.DCCode))
  || (paraName.ToLower() == Comparator.Supplierid && intSearch.Contains(t.SupplierId))
  || (paraName.ToLower() == Comparator.Doorid && intSearch.Contains(t.DoorId))
  || (paraName.ToLower() == Comparator.Carrierid && intSearch.Contains(t.CarrierId))
  || (paraName.ToLower() == Comparator.Buyer && strSearch.Contains(t.Buyer))
  )

paraName是通過bookingId ， dccode字符串搜索的，而intSearch包含多個bookingids 。

我可以在Linq查詢中使用謂詞來避免和/或使用此代碼中的條件嗎？

Answer 1

您可以只在確定要使用的參數的方法中構建表達式：

private Expression<Func<Foo, bool>> GetExpression(string param, string searchTerm)
{
    switch (param)
    {
        case "bar":
            return f => f.Bar.Contains(searchTerm);
        case "baz":
            return f => f.Baz.Contains(searchTerm);
        // ...
    }
}

然后這樣稱呼它：

var bars = (from c in collection select c).Where(GetExpression(param, searchTerm));