如何在实体框架查询中将DateTime转换为TimeSpan [英] How to convert DateTime to TimeSpan in Entity Framework query

问题描述

我在实体框架6中有此LINQ查询:

I have this LINQ query with Entity Framework 6:

var timeCapturesQuery = Context.TimeCaptures
    .Where(t =>
        && t.StartDateTime.TimeOfDay < endTime
        && t.EndDateTime.TimeOfDay > startTime);

EndTime和StartTime是类型TimeSpan的参数，StartDateTime和EndDateTime是datetime表中的列.

EndTime and StartTime are parmeters of type TimeSpan, StartDateTime and EndDateTime are columns on the table of datetime.

不幸的是，我在运行该错误时遇到了这个错误:

Unfortunately I get this error when it is run:

LINQ to Entities不支持指定的类型成员'TimeOfDay'.仅支持初始化程序，实体成员和实体导航属性.

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

如何在此LINQ查询中从DateTime(即SQL中的datetime中的time)中获取TimeSpan?

How can I get a TimeSpan from a DateTime (i.e. the time from datetime in SQL) in this LINQ query?

推荐答案

类似于

Looks like DbFunctions.CreateTime is what you're looking for:

当用作LINQ to Entities查询的一部分时，此方法将调用 规范的CreateTime EDM函数来创建新的TimeSpan对象.

When used as part of a LINQ to Entities query, this method invokes the canonical CreateTime EDM function to create a new TimeSpan object.

因此，要在两次之间获得结果，您可以:

So to get results between two times, you can:

var timeCapturesQuery = Context.TimeCaptures.Where(t =>
        DbFunctions.CreateTime(t.StartDateTime.Hour, t.StartDateTime.Minute, t.StartDateTime.Second) < endTime &&
        DbFunctions.CreateTime(t.EndDateTime.Hour, t.EndDateTime.Minute, t.EndDateTime.Second) > startTime);

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