Question

我有一个Apartments的列表，其中每个Apartment都有ApartmentRooms，每个ApartmentRoom都有DateBatches DateBatch 。每个Dates都有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列表，表示占用日期（每个拍摄日期一条记录）。

1.5-10.5
2.5-11.5
3.5-12.5
4.5-13.5
5.5-14.5

通过这个，您可以看到这间公寓有2个房间，其中房间1在下列日期为1.5,2.5,8.5和9.5，而房间2则占用5.5和6.5。

用户可以输入他想要留下的N天和X连续天数的期望值。

举一个例子，用户输入的时间从1.5到15.5并且他想要睡10个晚上，我需要列出所有公寓，其中至少有一个公寓房可用于任何可能的日期组合，这将是以下在这种情况下：

 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;
    }

到目前为止，我已经尝试了这个，它只适用于第一次foreach迭代，因为foreach将查询与AND条件连接，而不是OR标准，我认为这是一个非常糟糕的方法。

users

有什么建议吗？

Answer 1

To combine multiple conditions with OR, you can use (for example) LinqKit library. Install it via nuget, add using LinqKit; and then:

    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);
    }

Note that I also modified your logic. Of course, this logic is perfect candidate for unit-testing, and if you are working on a serious project - you should definely test it using in-memory EF provider (or mocking) for different conditions.

Answer 2

这是一个纯粹的（不需要外部包）LINQ to Entities解决方案。

首先确定可能的开始日期列表：

var startDates = Enumerable.Range(0, PeriodEnd.Subtract(PeriodStart).Days - StayDuration + 1)
    .Select(offset => PeriodStart.AddDays(offset))
    .ToList();

然后使用以下查询：

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))))));

此解决方案的好处是可以轻松扩展。上述查询返回可用的公寓，但不提供可用房间的信息以及何时 - 您可能需要向用户提供的信息。使用上述方法，您可以获得如下信息：

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 };

实体框架日期组合查询

2 个答案: