如何从存储过程结果实体框架创建列表

Question

我正在使用 ASP.NET MVC 和 EF 创建一个车辆预订应用程序，用户可以在该应用程序中在一个日期时间预订多辆车辆，如果他们愿意的话。我创建了一个存储过程来防止重复预订车辆，但在弄清楚如何将结果添加到列表中时遇到了麻烦。

示例：我想为 2018 年 12 月 18 日的 12:00 到 13:00 保留 Vehicle#1 和 Vehicle#2....存储过程转到 db 以发现 Vehicle#1 已经从12:00 至 13:00，但未预留车辆#2。由于运行了foreach，alreadyReservedVehicle 返回了.Count() = 0 的结果，因为它看到了最后一个结果，即 Vehicle#2 未被保留。它应该会显示一条错误消息，指出不允许重复预订，因为车辆#1 已被预订，但它不计算该预订。

有没有办法收集这两个结果并告诉应用程序因为这 2 辆车中的一辆被预订，所以这两辆车都不能被预订？

public ActionResult Create([Bind(Include = "ID,StartDate,EndDate,RequestorID,Destination,PurposeOfTrip,TransportStudentsFG,LastChangedBy,LastChangedDate,VehicleList,ThemeColor")] Reservations reservation)
{
    if (ModelState.IsValid)
    {
        var selectedVehicles = reservation.VehicleList.Where(x => x.IsChecked == true).ToList();
        List<usp_PreventDoubleBooking_Result> alreadyReservedVehicle = null;

        // get each vehicle that was selected to be reserved then check db to make sure it is available
        foreach (var selectedVehicle in selectedVehicles) 
        {             
            using (VehicleReservationEntities db = new VehicleReservationEntities())
            {
                alreadyReservedVehicle = db.usp_PreventDoubleBooking(selectedVehicle.ID, reservation.StartDate, reservation.EndDate).ToList();                             
            }
        }

        if (alreadyReservedVehicle.Count() == 0) // create a new reservation if the vehicle is available at the selected date and time
        {
            db.Reservations.Add(reservation);
            reservation.LastChangedDate = DateTime.Now;
            db.SaveChanges();
        }
        else
        {
            //return error message on page if vehicle is already reserved
            TempData["Error"] = "Double booking of vehicles is not allowed. Please choose another vehicle/time. Check the availability timeline before reserving to ensure there are no errors. Thank you.";
            return RedirectToAction("Create");
        }
    }
}

以上是我到目前为止所拥有的，并且我知道我已经接近了，因为假设用户只尝试预订一辆已经预订的车辆，我所拥有的将起作用。当他们尝试为多辆车创建预订时，代码仅计算列表中的最后一辆车，并将其用作确定是否保存预订的结果。

我考虑将条件语句移到 foreach 中，但我不希望为每个选定的车辆保存预订...这没有任何意义，因为只有 1 个预订要保存，它只有多辆可以与之关联的车辆。

这是查找预留车辆的存储过程：

SELECT 
    v.ID, r.StartDate, r.EndDate 
FROM 
    dbo.Reservations r
JOIN 
    dbo.ReservationToVehicle rtv ON r.id = rtv.ReservationID
JOIN 
    dbo.Vehicles v ON v.ID = rtv.VehicleID
WHERE
    (v.ID = @VehicleID)
    AND (r.StartDate <= @NewEndDate) 
    AND (r.EndDate >= @NewStartDate)

那么我怎样才能让alreadyReservedVehicle List 将每个结果添加到列表中，以便我可以确定List 是否实际上有一个为0 的Count？

更新：

这是存储过程的模型

public partial class usp_PreventDoubleBooking_Result
{
    public int ID { get; set; }
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
}

Answer 1

public ActionResult Create(/*Bind attribute omitted*/ Reservations reservation)
{
    if (ModelState.IsValid)
    {
        // Is 'IsChecked' nullable? If not, "== true" is redundant.
        var selectedVehicles = reservation.VehicleList.Where(x => x.IsChecked == true).ToList();

        // get each vehicle that was selected to be reserved then check db to make sure it is available
        using (VehicleReservationEntities db = new VehicleReservationEntities())
        {
            foreach (var selectedVehicle in selectedVehicles)
            {
                // 'alreadyReservedVehicle' can be declared here because you don't need to let it
                // out of its cage, I mean the loop.
                List<usp_PreventDoubleBooking_Result> alreadyReservedVehicle =
                    db.usp_PreventDoubleBooking(selectedVehicle.ID, reservation.StartDate, reservation.EndDate).ToList();

                if (alreadyReservedVehicle.Count() > 0)
                {
                    //return error message on page if vehicle is already reserved
                    TempData["Error"] = "Double booking of vehicles is not allowed. Please choose another vehicle/time. Check the availability timeline before reserving to ensure there are no errors. Thank you.";
                    return RedirectToAction("Create");
                }
            }
        }

        // create a new reservation if the vehicle is available at the selected date and time
        db.Reservations.Add(reservation);
        reservation.LastChangedDate = DateTime.Now;
        db.SaveChanges();
    }
}

Answer 2

你可以这样做：

var preventDoubleBookingList= await context.Database.SqlQuery<usp_PreventDoubleBooking>("sproc_name", prams_here).ToListAsync();

您必须创建一个与存储过程匹配的模型。