EF 4 CTP 5 Complex query - entity-framework

Question

I have a model like the following:
public class Customer
{
public int Id { get; set; }
public string Name { get; set; }
public ICollection<Order> Orders { get; set; }
}
public class Order
{
public int Id { get; set; }
public DateTime DateTime { get; set; }
public Customer Customer { get; set; }
public ICollection<OrderLine> OrderLines { get; set; }
}
public class OrderLine
{
public int Id { get; set; }
public Product Product { get; set; }
public int Price { get; set; }
public int Quantity { get; set; }
}
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public Category Category { get; set; }
}
public class Category
{
public int Id { get; set; }
public string Name { get; set; }
}
I am using this infrastructure.
My aggregate roots are Customer, Order, Product. I did not include the mappings here as they are straight forward.
var customers = unitOfWork.Customers.FindAll();
var orders = unitOfWork.Orders.FindAll();
var products = unitOfWork.Products.FindAll();
var query = ......
Using LINQ, how would you select all customers that have orders for products in the "Beverages" category?
All samples I have seen on the web are very basic queries nothing advanced.

Answer 1

i found http://msdn.microsoft.com/en-us/vbasic/bb737909
May be your query should look like:
from c in unitOfWork.Customers
join o in unitOfWork.Orders on o.Customer = c
join ol in unitOfWork.OrderLines on ol.Order = o
where ol.Product.Category.Name == "Beverages"
select c
And it is necessary to add all parent-object-properties

Answer 2

This might work or not:
from customer in customers
where customer.Orders.Any(
o => o.OrderLines.Any(l => l.Product.Category.Name == "Beverages")
select customer
(I'm assuming you forgot the relationship between Product and Category)