LINQ to Entities不支持“TimeOfDay” - 在Linq 2 SQL中查找总秒数 [英] 'TimeOfDay' is not supported in LINQ to Entities - Find total seconds in Linq 2 SQL

问题描述

当我执行以下操作时：

[EdmFunction("Edm", "TruncateTime")]
public static DateTime? TruncateDateTime(DateTime? inputDate)
{
    return inputDate.HasValue ? inputDate.Value.Date : (DateTime?)null;
}

 [EdmFunction("Edm", "TotalSeconds")]
public static double? GetTotalSeconds(DateTime? inputDate)
{
    return inputDate.HasValue ? inputDate.Value.TimeOfDay.TotalSeconds: (double?)null;
}

var employeeSelection = (from c in MyContext.Employees.Where(c => c.From.HasValue && c.To.TimeOfDay.TotalSeconds != 0)
...
select new Employee

{


 To = c.To != DateTime.MinValue && c.To.TimeOfDay.TotalSeconds != 0 ? TruncateDateTime(c.To).Value :
              c.To != DateTime.MinValue && c.To.TimeOfDay.TotalSeconds == 0 ? c.From.Value.AddMinutes(30) :  DateTime.MinValue

}

我得到这个：

附加信息：LINQ to Entities中指定的类型成员TimeOfDay不是
，只有初始化器，实体成员和
实体导航属性。

Additional information: The specified type member 'TimeOfDay' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

当我尝试这个：

var employeeSelection = (from c in MyContext.Employees.Where(c => c.From.HasValue && GetTotalSeconds(c.To) != 0)
...
select new Employee

{


 To = c.To != DateTime.MinValue && GetTotalSeconds(c.To) != 0 ? TruncateDateTime(c.To).Value :
              c.To != DateTime.MinValue && GetTotalSeconds(c.To) == 0 ? c.From.Value.AddMinutes(30) :  DateTime.MinValue

}

我得到：

附加信息：指定的方法
'System.Nullable 1 [系统.Double]
GetTotalSeconds（System.Nullable 1 [System.DateTime]）'在类型
'GetDateRangeMethod'不能被翻译成LINQ to Entities
存储表达式。

Additional information: The specified method 'System.Nullable1[System.Double] GetTotalSeconds(System.Nullable1[System.DateTime])' on the type 'GetDateRangeMethod' cannot be translated into a LINQ to Entities store expression.

如何找到Linq到SQL的总秒数？

How can I find the total seconds in Linq to SQL ?

感谢

推荐答案

尝试使用 SqlFunctions.DatePart 。

而不是

var employeeSelection = (from c in MyContext.Employees
          .Where(c => c.From.HasValue && GetTotalSeconds(c.To) != 0)

更改为

var employeeSelection = (from c in MyContext.Employees
          .Where(c => c.From.HasValue && SqlFunctions.DatePart("second", c.To) != 0)

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