问题
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?
回答1:
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.
来源：https://stackoverflow.com/questions/4811557/ef-ctp5-strongly-typed-eager-loading-how-to-include-nested-navigational-prop