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.

 

Well I still have the problem. 

during the ctor of my ViewModel I want to create an entity and it fails the first time but will success all the others times.

It's like the first time something is missing (an assembly not loaded or found ?).

in the server I have :

Patients.Server.Domain : this is were the edmx is located. This assembly is perfectly added into the CompositionHost 

In the client I have :

Patients.Server.Domain : hosting the Designer.cs file and my repository from the edmx above.

PreAdmission.Client.Implementation : hosting the Views/Viewmodels, this assembly have a reference to Patients.Server.Domain (copy local is set to true)

Here is the method loading the xap where my view/vewmodel is located.

The uri of the catalog is "\ClientBin\PreAdmission\PreAdmission.Client.Implementation.xap" which is the assembly 

having a reference to Patients.Client.Domain

the exception raised by the first access to "var patient = new Patient();" :

   

 Below, the Logfile

 

 

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

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

I found out the problem, here is what I did :

1. I added to my silverlight application a reference to the assembly on the client hosting our Devforce autogenerated file. Before this reference existed only in the assembly where I have my ViewModel.

2. then I added to the web.config the connection string for my model.

Now I don't like this solution because I lose all the benefits from MEF, I need to be able to discover those services.

I tried to add in the global.asax (as suggested in the error message) the following line (without adding a reference to my assembly in the client) but it doesn't work : 

IdeaBlade.Core.Composition.CompositionHost.SearchPatterns.Add("MyClientAssemblyWithMyModel.dll"); 

Is there a way to not have to add a reference to all my assemblies hosting my models  in the client application ?

regards,

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 :