Question

In my App.xaml.cs I have

private void InitializeContainer()
{
    var catalogs = new AggregateCatalog();

    var catalog = new AssemblyCatalog(Assembly.GetExecutingAssembly());
    catalogs.Catalogs.Add(catalog);

    // Also adding Interactions project
    catalog = new AssemblyCatalog(typeof(InteractionsService).Assembly);
    catalogs.Catalogs.Add(catalog);

    // initialize the main application composition host (container) 
    CompositionHost.Initialize(catalogs);
} 

However, when I try to get object initialized down a line like so:

this.InteractionsService = ServiceLocator.Current.GetInstance<IInteractionsService>();

I get exception that my ServiceLocator.Current is null.

How do I make it work?

Answer 1

I think you’re missing the call to ComposeParts or Compose in the set up of the CompositionContainer . Before you start to resolve instances via GetInstance.

There’s an MSDN walk through here, and some other samples here and here. The relevant code snippet:

private CompositionContainer _container

//your code

var batch = new CompositionBatch();
batch.AddPart(this);

_container.Compose(batch);

//or more simply
_container.ComposeParts(this) //if this method is supported