Silverlight 4 RIA Services - select first entity from EntitySet

Question

Hi, I'm working with Silverlight 4 on getting a single entity from an Entity Set. Doesn't sound hard?! Well, I simply can't get it working:

myDomainContext dc = new OrgUnitTestDomainContext();
OrgUnit ou;
ou=dc.OrgUnits[0]; //Error 1    The property or indexer 'System.ServiceModel.DomainServices.Client.EntitySet.List' cannot be used in this context because the get accessor is inaccessible
ou=dc.OrgUnits.First; //Error   2   ... does not contain a definition for 'First' and no extension method 'First' accepting a first argument
ou=dc.OrgUnits.Current; //Error 3   ... does not contain a definition for 'Current' and no extension method 'Current' accepting a first argument
ou=dc.OrgUnits.List.First; //Error  4   The property or indexer 'System.ServiceModel.DomainServices.Client.EntitySet.List' cannot be used in this context because the get accessor is inaccessible
ou=dc.OrgUnits.List.Current; //as Error 3

Don't I see the forest because of the trees, or do I really have to do ugly things like:

//That works
System.Collections.Generic.IEnumerator<OrgUnit> enu = dc.OrgUnits.GetEnumerator();
enu.MoveNext();
ou = enu.Current;

//That works, but its ugly, too
foreach (OrgUnit ou in dc.OrgUnits)
{
    SelectedOrgUnit = ou;
    break;
}

Has anyone an idea what's wrong there - as said, I'm only trying to get a single entity? Best Regards, rwh

Answer 1

You haven't loaded any data into your DomainContext. It is empty until you load the data you require. (Unless you have done so in your XAML??)