EF LINQ包括多个和嵌套实体 [英] EF LINQ include multiple and nested entities

问题描述

好吧，我有以下层次结构三层次的实体：课程 - >模块 - >第一章

Ok, I have tri-leveled entities with the following hierarchy: Course -> Module -> Chapter

下面是原来的EF LINQ语句：

Here was the original EF LINQ statement:

Course course = db.Courses
                .Include(i => i.Modules.Select(s => s.Chapters))
                .Single(x => x.Id == id); 

现在，我想包括所谓的实验室另一个实体这与课程相关的。

Now, I want to include another entity called Lab which is associated with a course.

我如何包括实验室实体？

How do I include the Lab entity?

我试过以下，但它没有工作：

I tried the following but it didn't work:

Course course = db.Courses
                .Include(i => i.Modules.Select(s => s.Chapters) && i.Lab)
                .Single(x => x.Id == id); 

这包括第二实体的任何想法？

Any ideas on including the 2nd Entity?

任何一块意见或信息将是非常美联社preciated。谢谢！

Any piece of advise or information would be highly appreciated. Thanks!

推荐答案

您是否尝试过只需添加另一个包含：

Have you tried just adding another Include:

Course course = db.Courses
                .Include(i => i.Modules.Select(s => s.Chapters))
                .Include(i => i.Lab)
                .Single(x => x.Id == id);

由于包括您的解决方案失败不采取布尔运算符

Include(i => i.Modules.Select(s => s.Chapters) &&          i.Lab)
                           ^^^                  ^             ^ 
                          list           bool operator    other list

更新
要了解更多信息，请下载 LinqPad 并通过样本的样子。
我认为这是熟悉的LINQ和Lambda的最快方式。

Update To learn more, download LinqPad and look through the samples. I think it is the quickest way to get familiar with Linq and Lambda.

作为一个开始 - 选择之间的差异和包含是与一个选择决定的的 的您想返回（又名投影）的东西。在include是一个 预先加载的功能，告诉你希望它包括来自其他表中的数据实体框架。

As a start - the difference between Select and Include is that that with a Select you decide what you want to return (aka projection). The Include is a Eager Loading function, that tells Entity Framework that you want it to include data from other tables.

在包括语法，也可以在字符串。像这样的：

The Include syntax can also be in string. Like this:

           db.Courses
            .Include("Module.Chapter")
            .Include("Lab")
            .Single(x => x.Id == id);

但在 LinqPad 样解释这更好的。

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