Problem with RIA Services and POCO classes, associated child collection not being sent

Here's my setup: I have some "data", which is actually a graph of objects (DTOs representing SSAS objects) that I want serialized and sent via RIA Services for consumption by a silverlight app. Here's a simple example of that:

public class Database
{
   开发者_JS百科[Key]
   public int ID { get; set;}

   public string Name { get; set;}

   [Include]
   [Association("DatabaseCue", "ID", "DatabaseID"]
   public IEnumerable<Cube> Cubes { get; set;}
}
public class Cube
{
   [Key]
   public int ID { get; set;}

   public int DatabaseID { get; set;}

   public string Name { get; set;}

   // other Cube properties
}

And I have a DomainService:

[EnableClientAccess()]
public class AmoService : DomainService
{
   public IQueryable<Database> GetDatabases()
   {
       return myAmoAdapter.GetDatabases();
   }
}

myAmoAdapter.GetDatabases() retrieves the Database collection, filling also its child Cubes collection just fine, however, in the client side, the cubes collection is empty! I can't figure out how to make this work! (or maybe it just won't?!)

Anybody know why this isn't working and how to fix it? I would be grateful.

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The only thing that appears different from how I do this is public IEnumerable Cubes { get; set;}. I would usually do that as:

public List<Cube> Cubes { get; set;}

Also, you need a Composition tag as follows:

[Include]
[Composition]
[Association("DatabaseCue", "ID", "DatabaseID"]
public IEnumerable<Cube> Cubes { get; set;}

---

Did you check on the client side if it has a an EntitySet for Cube?

If that is not available, then you also need to tell RIA Services that Cube is a class that should be generated on the client. You can do this by defining a dummy method like this on the server side:

public IQueryable<Cube> GetCubesDummy()
{
   return new List<Cube>().AsQueryable();
}

If the EntitySet exists, you should also check if the Foreign-Keys are ok. Just because the collection is populated on the server, it doesn't mean that the DatabaseID in the Cube elements is correct.

---

You can explicitly set the IsForeignKey property of the Association attribute on the Database object

[Include]
[Association("DatabaseCue", "ID", "DatabaseID", IsForeignKey = false]
public IEnumerable<Cube> Cubes { get; set;}

---

One thing you might want try is to initialize the Cubes collection on Database in the constructor.

public class Database
{
  public Database
  {
    Cubes = new List<Cube>();
  }

  [Key]
  public int ID { get; set;}

  public string Name { get; set;}

  [Include]
  [Association("DatabaseCue", "ID", "DatabaseID"]
  public IEnumerable<Cube> Cubes { get; set;}
}

RIA Services can sometimes exhibit some strange behavior if Associated Entity collections are not initialized.

---

I had a similar problem and it turned out that it would work if I added the child to the parent's collection and also specifically set the parent id.

So

    Database db = ...

    db.Cubes.Add(new Cube(){ID=1, DatabaseID=db.ID, Name = "Cube1" });

if I didn't have the DatabaseID=db.ID they would be set to zero and nothing would be returned by RIA Services. Bug?