c# - 在linq查询返回匿名类型中将可为空的int转换为int

Question

此处是返回匿名类型 的实体查询的简单 linq。问题是其中一个 int? 值像参数一样使用来获取另一个值 int。

我知道的所有方法都行不通。请告知如何解决此问题。

public IQueryable<toursistdata> GetxTouristByCategory(string category)
        {
            var now = System.DateTime.MinValue;
            int i;
            switch (category)
            {
                case "arrival":
                    now = System.DateTime.Now.AddDays(-3);
                    var arrival = from a in db.xTourist
                                  where a.ArrDate >= now && a.Room == null
                                  select new toursistdata
                                  {
                                      kodt = a.Kod,
                                      name = a.Name,
                                      paxad = a.Paxad,
                                      paxch = a.Paxch,
                                      **//Here is h.Kod is int but KodH is int?**
                                      hotel = (from h in db.Address where h.Kod = (int)a.KodH.HasValue select h.NameC).FirstOrDefault(),
                                      room = a.Room,
                                      arrdate = a.ArrDate,
                                      arrtime = a.ArrTime,
                                      arrflight = a.ArrFl,
                                      depdate = a.DepDate,
                                      deptime = a.Deptime,
                                      depflight = a.DepFlight,
                                      transfer = a.Transfer
                                  };
                                  return arrival;
                case "inhouse":
                    now = System.DateTime.Today;
                    //return db.xTourist.AsQueryable().Where(p => p.Датапр >= now && p.Номер != null).OrderByDescending(p => p.Датапр);
                default:
                    //return db.xTourist.AsQueryable();
            }
        }

Answer 1

首先，您的等号运算符中缺少一个“=”。那么，如果你想比较一个int和一个int？您可以使用 Null Coalescing 运算符 ??为 null-case 提供默认值，然后将其转换为 int:

h.Kod == (a.KodH ?? 0)