实体框架 - 如何获取过滤的主记录和过滤的详细记录？

发布于 2024-10-18 05:21:35 字数 856 浏览 1 评论 0原文

我的班级关系：ClassMaster 1----* ClassSessions
我的目标：返回所有具有 StartDateTime 大于当前日期的 ClassSession 的 ClassMaster，以及这些 ClassSession（按日期过滤）。

在 T-SQL 中，我会这样做：

select *
   from ClassSession
   join ClassMaster on ClassMaster.ClassId = ClassSession.ClassId
   Where ClassSession.StartDateTime > getdate()

我需要在 Entity Framework 4 查询中实现相同的结果。这就是我认为它会起作用的，但没有：

   var classes = ctx.ClassSessions
                 .Include("ClassMasters")
                 .Where(s => s.StartDateTime > DateTime.Now)
                 .Select(s => s.ClassMaster)
                 .ToList();

这给了我所有具有 StartDateTime > 的 ClassSession 的 ClassMaster。当前日期，但 ClassSessions 属性填充了所有 ClassSession，包括早于当前日期的。我只想要 StartDateTime > 的 ClassSessions当前日期。

我做错了什么？

非常感谢！

原文

My class relationship: ClassMaster 1----* ClassSessions
My Goal: Return all ClassMasters that have ClassSessions with StartDateTime greater than the current date, along with these ClassSessions (filtered by date).

In T-SQL I'd do this:

select *
   from ClassSession
   join ClassMaster on ClassMaster.ClassId = ClassSession.ClassId
   Where ClassSession.StartDateTime > getdate()

I need to realize the same results in an Entity Framework 4 query. This is what I thought it would work, but does not:

   var classes = ctx.ClassSessions
                 .Include("ClassMasters")
                 .Where(s => s.StartDateTime > DateTime.Now)
                 .Select(s => s.ClassMaster)
                 .ToList();

This give's me all the ClassMasters that have some ClassSession with StartDateTime > current date, but the ClassSessions property comes filled with all ClassSessions, including older than current date. I only want ClassSessions with StartDateTime > current date.

What am I doing wrong?

Thank you very much!

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南七夏 2024-10-25 05:21:35

var masters = ctx.ClassMasters
         .Where(cm => cm.ClassSessions.Any(cs => cs.StartDateTime > DateTime.Now))
         .Select(cm => new { ClassMaster = cm, ClassSessions = cm.ClassSessions.Where(cs => cs.StartDateTime > DateTime.Now)
         .ToList().Select(e => e.ClassMaster);

如果您在上下文中的某个位置加载了所有 ClassSession 对象，您仍然可以执行以下操作：

var masters = ctx.ClassMasters
         .Where(cm => cm.ClassSessions.Any(cs => cs.StartDateTime > DateTime.Now))
         .Select(cm => new ClassMasterWithSessionModel{ ClassMaster = cm, ClassSessions = cm.ClassSessions.Where(cs => cs.StartDateTime > DateTime.Now)
         .ToList();

public class ClassMasterWithSessionModel {
    ClassMaster ClassMaste { get; set; }
    IEnumerable<ClassSession> ClassSessions { get; set; }
}

var masters = ctx.ClassMasters
         .Where(cm => cm.ClassSessions.Any(cs => cs.StartDateTime > DateTime.Now))
         .Select(cm => new { ClassMaster = cm, ClassSessions = cm.ClassSessions.Where(cs => cs.StartDateTime > DateTime.Now)
         .ToList().Select(e => e.ClassMaster);

In case you loaded all ClassSession objects somewhere in context, you can still do this:

var masters = ctx.ClassMasters
         .Where(cm => cm.ClassSessions.Any(cs => cs.StartDateTime > DateTime.Now))
         .Select(cm => new ClassMasterWithSessionModel{ ClassMaster = cm, ClassSessions = cm.ClassSessions.Where(cs => cs.StartDateTime > DateTime.Now)
         .ToList();

public class ClassMasterWithSessionModel {
    ClassMaster ClassMaste { get; set; }
    IEnumerable<ClassSession> ClassSessions { get; set; }
}

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