实体框架可以通过相关实体的属性对实体进行排序吗？ [英] Can Entity Framework sort entities by properties on a related entity?

问题描述

假设我有以下Foo和Bar实体：

  class Foo {
 int FooId ; 
 string FooName; 
} 
 
 class Bar {
 int BarId; 
 Foo RelatedFoo; 
 string BarName; 
} 
  

我们还假设我希望RelatedFoo默认为延迟加载

在实体框架中，是否可以执行一个查询，返回一个枚举的Bar实体，其中元素按bar.RelatedFoo.FooName排序？ / p>

如果是这样，这可以在固定数量的数据库查询中完成吗？我想避免执行 N + 1个查询。

如果没有，这是否可能在另一个.NET ORM框架中？

解决方案

  var bars = _context.Bars.OrderBy（b => b.RealtedFoo.FooName）
  

您可能还只想带回那些 RealtedFoo 不为空的栏

  var bars = _context.Bars.Where（b => b.RelatedFoo！= null）.OrderBy（b => b.RealtedFoo.FooName）
  

更新：

  //对于EF只有
 _context.Configuration.LazyLoadingEnabled = false 
 
 //如果你想带回RealtedFoo，然后包含它。 
 //否则，您只能查询它，而不使用Include（）扩展名。 
 var bars = _context.Bars.Include（b => b.RealtedFoo）.Where（b => b.RelatedFoo！= null）.OrderBy（b => b.RealtedFoo.FooName）
  

Suppose I have the following "Foo" and "Bar" entities:

class Foo {
   int FooId;
   string FooName;
}

class Bar {
   int BarId;
   Foo RelatedFoo;
   string BarName;
}

Let's also suppose that I want "RelatedFoo" to be lazy-loaded by default.

In Entity Framework, is it possible to do a query that returns an enumerable of "Bar" entities where elements are sorted by "bar.RelatedFoo.FooName"?

If so, can this be done in a fixed number of database queries? I would like to avoid doing N+1 queries.

If not, is this possible in another .NET ORM framework?

解决方案

var bars = _context.Bars.OrderBy(b => b.RealtedFoo.FooName)

You may also want to only bring back those bars that RealtedFoo is not null

var bars = _context.Bars.Where(b => b.RelatedFoo != null).OrderBy(b => b.RealtedFoo.FooName)

Update:

    //For EF only
    _context.Configuration.LazyLoadingEnabled = false

    //If you want to bring back RealtedFoo then include it. 
//Otherwise, you can just query for it and not use the Include() extension.
    var bars = _context.Bars.Include(b => b.RealtedFoo).Where(b => b.RelatedFoo != null).OrderBy(b => b.RealtedFoo.FooName)

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