LINQ to Entities无法识别方法'Int32 WeeksInYear（System.DateTime）'方法 [英] LINQ to Entities does not recognize the method 'Int32 WeeksInYear(System.DateTime)' method

问题描述

我有一个静态课程：

I have a static class:

public  class WeekInYear
    {
        //pass date = DateTime.Now 
        //return num of this week in calendar
        public static int WeeksInYear(DateTime date)
        {
            DateTimeFormatInfo dfi = DateTimeFormatInfo.CurrentInfo;           
            Calendar cal = dfi.Calendar;          
            return cal.GetWeekOfYear(date, dfi.CalendarWeekRule, dfi.FirstDayOfWeek);
        }
        
    }

这是我的linq：

In here is my linq:

int thisWeek = WeekInYear.WeeksInYear(DateTime.Now);
 model.NumOfUserCreatedOnThisWeek = Context.Accounts.Where(r => WeekInYear.WeeksInYear(r.CreatedDate) == thisWeek).Count();

然后我收到错误消息：

LINQ to Entities无法识别方法'Int32 WeeksInYear（系统。 DateTime）'method

then I get error message:
LINQ to Entities does not recognize the method 'Int32 WeeksInYear(System.DateTime)' method

推荐答案

我通过创建DateTimeExtensions方法更改它：

I change it by create a DateTimeExtensions method:

public static class DateTimeExtensions
    {
        public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
        {
            int diff = dt.DayOfWeek - startOfWeek;
            if (diff < 0)
            {
                diff += 7;
            }

            return dt.AddDays(-1 * diff).Date;
        }
    }

之后我用它发现：

After that I use it found:

DateTime thisMonday = DateTime.Now.StartOfWeek(DayOfWeek.Monday);
     DateTime thisSunday = thisMonday.AddDays(6);

     DateTime lastSunday = DateTime.Now.StartOfWeek(DayOfWeek.Sunday);
     DateTime lastMonday = lastSunday.AddDays(-6);

最后我改变了我的linq：

finally I change my linq:

model.NumOfUserCreatedOnLastWeek = Context.Accounts.Where(r => (r.CreatedDate >= thisMonday) && (r.CreatedDate <= thisSunday)).Count();

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