尝试将我们的 EF4 解决方案切换到 EF CTP5，但遇到了问题。
这是模型的相关部分：
相关关系：
- 一个县拥有许多城市
- 单个城市有单个州
现在，我想执行以下查询：
- 获取系统中的所有县，包括所有城市，以及这些城市的所有州。
在 EF4 中，我会这样做：
var query = ctx.Counties.Include("Cities.State");
在 EF CTP5 中，我们有一个强类型的 Include，它采用 Expression>。
我可以毫无问题地获取县的所有城市：
var query = ctx.Counties.Include(x => x.Cities);
但是我如何才能获取这些城市的州？
我使用的是纯 POCO，因此 County.Cities 是一个 ICollection，因此我无法执行此操作：
var query = ctx.Counties.Include(x => x.Cities.State)
正如 ICollection 所做的那样没有名为 State 的属性。
这几乎就像我需要使用嵌套的 IQueryable 一样。
有什么想法吗？在这种情况下我需要回退到魔术字符串 Include 吗？
Attempting to cutover our EF4 solution to EF CTP5, and ran into a problem.
Here's the relevant portion of the model:
The pertinent relationship:
- A single County has many Cities
- A single City has a single State
Now, i want to perform the following query:
- Get all Counties in the system, and include all the Cities, and all the State's for those Cities.
In EF4, i would do this:
var query = ctx.Counties.Include("Cities.State");
In EF CTP5, we have a strongly typed Include, which takes an Expression<Func<TModel,TProperty>>.
I can get all the Cities for the County no problem:
var query = ctx.Counties.Include(x => x.Cities);
But how can i get the State for those Cities too?
I am using pure POCO's, so County.Cities is an ICollection<City>, therefore i cannot do this:
var query = ctx.Counties.Include(x => x.Cities.State)
As ICollection<City> does not have a property called State.
It's almost like i need to use a nested IQueryable.
Any ideas? Do i need to fallback to the magic string Include in this scenario?
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为此，您可以使用Select方法：
在这里您可以找到另一个示例。
For that you can use you the Select method:
Here you can find another example.