How to load master-details data(more than 2 hierarchy) using WCF RIA Services

I'm trying to get my head around treeviews and am able to do two levels, but I'm stumped with adding the 3rd level. I assume you make a 3rd Hierarchical Template - but I'm not sure how this is loaded. I'm using the AdventureWorks database as sample data.

I'm using the Product, ProductCategory, and ProductSubCategory tables.

My Metadata looks like. (just the interesting bits)

public partial class Product
{
    public string Name { get; set; }

    public int ProductID { get; set; }

    public string ProductNumber { get;set; }

    public ProductSubcategory ProductSubcategory { get; set; }

    public Nullable<int> ProductSubcategoryID { get; set; }
}

public partial class ProductCategory
{
    public string Name { get; set; }

    public int Pro开发者_StackOverflowductCategoryID { get; set; }

    [Include]

    [Composition]

    public EntityCollection<ProductSubcategory> ProductSubcategory { get; set; }
}

public partial class ProductSubcategory
{
    public string Name { get; set; }

    [Include]

    [Composition]

    public EntityCollection<Product> Product { get; set; }

    public ProductCategory ProductCategory { get; set; }

    public int ProductCategoryID { get; set; }

    public int ProductSubcategoryID { get; set; }

My Queries look like :

public IQueryable<Product> GetProduct()
{
    return this.ObjectContext.Product;
}

public IQueryable<ProductCategory> GetProductCategory()
{
    return this.ObjectContext.ProductCategory.Include("ProductSubcategory");
}

public IQueryable<ProductSubcategory> GetProductSubcategory()
{
    return this.ObjectContext.ProductSubcategory.Include("Product");
}

My Code behind (which is where I'm having the problem understanding how to load two queries). I want to return Products under ProductSubCategory under ProductCategory.

public partial class Tree : Page
{
    public Tree()
    {
        InitializeComponent();

        AdventureWorksContext ads = new AdventureWorksContext();

        trvTree.ItemsSource = ads.ProductCategories;

        ads.Load(ads.GetProductCategoryQuery());           
    }
}

---

Try modifying your GetProductCategory query as such:

{
    return this.ObjectContext.ProductCategory.Include("ProductSubcategory").Include("ProductSubcategory.Product");
}

I don't know if it'll work in your case, where you want to build a tree, but it should include the data as needed.