EF CTP5 - Strongly-Typed Eager Loading - How to Include Nested Navigational Properties?

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 Cou开发者_StackOverflow中文版nty 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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For that you can use you the Select method:

var query = ctx.Counties.Include(x => x.Cities.Select(c => c.State))

Here you can find another example.