Linq-to-Entities：格式选择查询表达式中的日期 [英] Linq-to-Entities: Format Date in select query expression

问题描述

  nonBusinessDays =（ from ac in db.AdminCalendar 
其中ac.DateTimeValue> = calendarStartDate&& ac.DateTimeValue< = calendarEndDate&& ac.IsBusinessDay == false 
 select ac.MonthValue +/ + ac.DayOfMonth +/+ ac.FullYear）.ToList（）; 
  

但是，我得到以下错误消息：
无法投射类型系统.Nullable`1'键入'System.Object'LINQ to Entities只支持转换Entity Data Model原始类型。

除了迭代之外，还有什么办法吗通过结果集？
谢谢！
Abe

解决方案

我发现一个解决方法：

  nonBusinessDays =（from $ in 
（from ac in db.AdminCalendar 
 where ac.DateTimeValue> = calendarStartDate&& ac.DateTimeValue< = calendarEndDate& ;& ac.IsBusinessDay == false 
 select ac.DateTimeValue）.ToList（）
 select string.Format（{0：M / d / yyyy}，dt））。ToList（） ; 
  

I am trying to get a formatted date string directly from a LINQ-to-Entities query expression.

nonBusinessDays = (from ac in db.AdminCalendar
                   where ac.DateTimeValue >= calendarStartDate && ac.DateTimeValue <= calendarEndDate && ac.IsBusinessDay == false
                   select ac.MonthValue + "/" + ac.DayOfMonth + "/" + ac.FullYear).ToList();

But, I get the folloinw error message: "Unable to cast the type 'System.Nullable`1' to type 'System.Object'. LINQ to Entities only supports casting Entity Data Model primitive types."

Is there any way to do this besides iterating through the result set? Thanks! Abe

解决方案

I found one workaround:

 nonBusinessDays = (from dt in
                            (from ac in db.AdminCalendar
                             where ac.DateTimeValue >= calendarStartDate && ac.DateTimeValue <= calendarEndDate && ac.IsBusinessDay == false
                             select ac.DateTimeValue).ToList()
                    select string.Format("{0:M/d/yyyy}", dt)).ToList();

这篇关于Linq-to-Entities：格式选择查询表达式中的日期的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！