Question

I am new to Silverlight RIA services and I have a basic working prototype that utilizes the RIA services with the EntityFramework. Now that I have moved on to the actual project, I am wondering how to utlize non-EntityFramework objects but still use RIA Controls such as the System.Windows.Controls.DomainServices.DomainDataSource so that I can paginate, etc. For example, in my working prototype, I have:

[EnableClientAccess()]
public class RequestService : LinqToEntitiesDomainService<MyEntities>
{
    public IQueryable<RequestData> GetRequests()
    {
        ... LINQ query removed ...
    }
}

When I change IQueryable<RequestData> to IQueryable<MyRequestData> where MyRequestData is a custom public class I created (and convert the Entity data to ) and then rebuild the application, the client Silverlight application no longer sees the query (build errors).

So my question is, how can I leverage these custom objects in a similar fashion to the EntityFramework objects so that I can still apply pagination, etc?

Answer 1

You can create a POCO class and assign the Key attribute to one of its properties like this…

public class MyClass
{
    [Key]
    public string Name { get; set; }
    public int Age { get; set; }
}

Then you can create a DomainService class that contains a way to get at the POCO class like this…

[EnableClientAccess()]
public class DomainService1 : DomainService
{
    public List<MyClass> GetData()
    {
        return new List<MyClass>(){new MyClass{Name = "Henry", Age = 33}};
    }
}

This method returns a list of MyClass with a single element in it. But you could return almost anything.

Then on the client side you can invoke the Domain Service like this…

 public MainPage()
        {
            InitializeComponent();
            DomainService1 ds1 = new DomainService1();
            var x = ds1.Load(ds1.GetDataQuery());
            x.Completed += new EventHandler(x_Completed);
        }
        void x_Completed(object sender, EventArgs e)
        {
            // process the results here
        }

In the event callback, you can cast the sender argument to a LoadOperation and get the data you wanted…

The trick comes from using the ‘Key’ attribute. That makes the whole thing work.