Question

我知道这个问题看起来像是重复的，但似乎每个案例都有它自己的解决方案，我找不到这个例外的正确解释：

LINQ to Entities无法识别方法＆＃39;布尔值 DateReservationOnTheSameWeek（的System.DateTime）＆＃39;方法和这种方法无法翻译成商店表达。

我只是想比较两个日期是否在同一个iso周，这里是我的代码：

public class Reservation
{
    public DateTime DateReservation { get; set; }
    // other methods and properties
    public static bool IsOnQuota(Reservation item)
    {
        using (var ctx = new SchedulingToolContext())
        {
            float qteSem = ctx.Reservations.Where(k => k.CltNameAlpha == item.CltNameAlpha 
                    && k.DateReservation.Year == item.DateReservation.Year
                    && item.DateReservationOnTheSameWeek(k.DateReservation) // this causes the exception
                    ).Sum(k => k.Qte);
            var q = ctx.Quotas.Where(k => k.Id == item.IdQuota).FirstOrDefault();
            return q.QteMaxJour >= item.Qte && q.QteMaxSemaine >= qteSem;
        }
    }
    private static int GetIso8601WeekOfYear(DateTime time)
    {
        DayOfWeek day = System.Globalization.CultureInfo.InvariantCulture.Calendar.GetDayOfWeek(time);
        if (day >= DayOfWeek.Monday && day <= DayOfWeek.Wednesday)
        {
            time = time.AddDays(3);
        }
        return System.Globalization.CultureInfo.InvariantCulture.Calendar.GetWeekOfYear(time, System.Globalization.CalendarWeekRule.FirstFourDayWeek, DayOfWeek.Monday);
    }

    private bool DateReservationOnTheSameWeek(DateTime date)
    {
        return GetIso8601WeekOfYear(this.DateReservation) == GetIso8601WeekOfYear(date);
    }
}

我无法弄清楚这个谓词失败的原因。编辑：我无法计算查询中的谓词，因为它取决于k是lambda函数的一部分。

Answer 1

也许使用SqlFunctions.DatePart和ISO_WEEK会有所帮助

using (var ctx = new SchedulingToolContext())
{
    float qteSem = ctx.Reservations.Where(k => k.CltNameAlpha == item.CltNameAlpha
                        && k.DateReservation.Year == item.DateReservation.Year
                        && SqlFunctions.DatePart("isowk", this.DateReservation) ==  SqlFunction.DatePart("isowk", k.DateReservation) 
                        ).Sum(k => k.Qte);
                var q = ctx.Quotas.Where(k => k.Id == item.IdQuota).FirstOrDefault();
                return q.QteMaxJour >= item.Qte && q.QteMaxSemaine >= qteSem;
}

LINQ不接受谓词中的静态函数：LINQ to Entities无法识别方法

1 个答案: