NullReferenceException during Entity creation

Hi,

I have a problem accessing DevForce entities and  EntityManager from my silverlight app. It's an application using Unity and MEF for service discovery. The architecture of this application was initialy done for a RIA approach but I am testing it with DevForce.

In the ViewModel, whenever I try to create a new entity (using the syntax "new myentity()" or "myentitymanager.CreateEntity<myentity>().") I get a NullReferenceException.

In the .web service I added all the ideablade reference with copy local to true. In the global.asax I added  HostingEnvironment.RegisterVirtualPathProvider(new IdeaBlade.EntityModel.Web.ServiceVirtualPathProvider());

http://localhost:27829/EntityService.svc show a page saying something like "the metadata is actually desactivated"

Any idea what could be the problem or where should I look  ?

Here is the exception log :

Here are the TraceViewer's log :

Did you clear the SearchPatterns before adding to it? i.e.

IdeaBlade.Core.Composition.CompositionHost.SearchPatterns.Clear();

 

Since the problem only occurs the first time you construct the entity, it's likely a timing issue between DevForce's loading of metadata for the dynamic content and your constructor call.  

 

When dynamic content is loaded there are two possible events to listen for, depending on how you load the content.  The CompositionHost will fire a Recomposed event, and if you're using a DynamicXap, that will fire a Loaded event.  In either case, the event signals that DevForce has finished loading the dynamic content.  In your case, DevForce hasn't yet constructed metadata for entities in your model, so that ugly NullReferenceException is thrown because the metdata is missing.

 

Here's information from the DRC on the various ways to load dynamic content, and how to listen for its events - http://drc.ideablade.com/xwiki/bin/view/Documentation/on-demand-discovery.