[英]Entity Framework date combination query
我有一個Apartments
列表,每個Apartment
都有它的ApartmentRooms
,每個ApartmentRoom
都有DateBatches
。 每個DateBatch
都有Dates
列表,表示占用日期(每個拍攝日期一條記錄)。
Apartment 1
Room 1
DateBatch
1.5.2015
2.5.2015
DateBatch 2
8.5.2015
9.5.2015
Room 2
DateBatch
5.5.2015
6.5.2015
通過這個,您可以看到這間公寓有2個房間,其中1號房間在下列日期分別為1.5,2.5,8.5和9.5,而房間2則分別為5.5和6.5。
用戶可以輸入他想要留下的N天和X連續天數的期望時段。
舉例來說,用戶輸入的時間從1.5到15.5並且他想要睡10個晚上,我需要列出所有公寓,其中至少有一個公寓房可用於任何可能的日期組合,在這種情況下將遵循:
1.5-10.5
2.5-11.5
3.5-12.5
4.5-13.5
5.5-14.5
到目前為止,我已經嘗試過這個,它只適用於第一次foreach迭代,因為foreach將查詢與AND標准連接,而不是OR標准,我認為這是一個非常糟糕的方法。
public static IQueryable<Apartment> QueryByPeriod(this IQueryable<Apartment> apartments, DateTime PeriodStart, DateTime PeriodEnd, int StayDuration)
{
var possibleDateRanges = new List<List<DateTime>>();
//set all possible start dates for the desired period
for (var i = PeriodStart; i <= PeriodEnd.AddDays(-StayDuration); i = i.AddDays(1))
{
List<DateTime> dates = new List<DateTime>();
foreach(var date in i.DateRange(i.AddDays(StayDuration-1)))
{
dates.Add(date);
}
possibleDateRanges.Add(dates);
}
//filter by date range
//select apartment rooms where one of possible combinations is suitable for selected period
foreach (var possibleDates in possibleDateRanges)
{
apartments = apartments.Where(m => m.ApartmentRooms
.Any(g => g.OccupiedDatesBatches.Select(ob => ob.OccupiedDates).Any(od => od.Any(f => possibleDates.Contains(f.Date)))
) == false);
}
return apartments;
}
有什么建議?
要將多個條件與OR組合,您可以使用(例如)LinqKit庫。 通過nuget安裝, using LinqKit;
添加using LinqKit;
然后:
public static IQueryable<Apartment> QueryByPeriod(this IQueryable<Apartment> apartments, DateTime PeriodStart, DateTime PeriodEnd, int StayDuration) {
var possibleDateRanges = new List<Tuple<DateTime, DateTime>>();
// list all ranges, so for your example that would be:
//1.5-10.5
//2.5-11.5
//3.5-12.5
//4.5-13.5
//5.5-14.5
var startDate = PeriodStart;
while (startDate.AddDays(StayDuration - 1) < PeriodEnd) {
possibleDateRanges.Add(new Tuple<DateTime, DateTime>(startDate, startDate.AddDays(StayDuration - 1)));
startDate = startDate.AddDays(1);
}
Expression<Func<Apartment, bool>> condition = null;
foreach (var range in possibleDateRanges) {
Expression<Func<Apartment, bool>> rangeCondition = m => m.ApartmentRooms
// find rooms where ALL occupied dates are outside target interval
.Any(g => g.OccupiedDatesBatches.SelectMany(ob => ob.OccupiedDates).All(f => f.Date < range.Item1 || f.Date > range.Item2)
);
// concatenate with OR if necessary
if (condition == null)
condition = rangeCondition;
else
condition = condition.Or(rangeCondition);
}
if (condition == null)
return apartments;
// note AsExpandable here
return apartments.AsExpandable().Where(condition);
}
請注意,我也修改了你的邏輯。 當然,這個邏輯是單元測試的理想選擇,如果你正在開展一個嚴肅的項目 - 你應該使用內存中的EF提供程序(或模擬)來針對不同的條件進行定義測試。
這是一個純粹的(不需要外部包)LINQ to Entities解決方案。
首先確定可能的開始日期列表:
var startDates = Enumerable.Range(0, PeriodEnd.Subtract(PeriodStart).Days - StayDuration + 1)
.Select(offset => PeriodStart.AddDays(offset))
.ToList();
然后使用以下查詢:
var availableApartments = apartments.Where(a => a.ApartmentRooms.Any(ar =>
startDates.Any(startDate => !ar.OccupiedDatesBatches.Any(odb =>
odb.OccupiedDates.Any(od =>
od.Date >= startDate && od.Date < DbFunctions.AddDays(startDate, StayDuration))))));
該解決方案的好處是可以輕松擴展。 上述查詢返回可用的公寓,但不提供可用房間的信息以及何時 - 您可能需要向用戶提供的信息。 使用上述方法,您可以獲得如下信息:
public class AvailableApartmentInfo
{
public Apartment Apartment { get; set; }
public Room Room { get; set; }
public DateTime StartDate { get; set; }
}
var availableApartmentInfo =
from a in apartments
from ar in a.ApartmentRooms
from startDate in startDates
where !ar.OccupiedDatesBatches.Any(odb =>
odb.OccupiedDates.Any(od =>
od.Date >= startDate && od.Date < DbFunctions.AddDays(startDate, StayDuration)))
select new AvailableApartmentInfo { Apartment = a, Room = ar, StartDate = startDate };
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