Resetting a Control loaded using MEF

I have used MEF to load in external XAPs, this works great. But when I navigate away from the page with the loaded control, then go back to it, the control is in the exact state I left it.

Now sometimes this is great, but not for the project I working on.

How do I reset the control to its initial state?

The control is loaded (successfuly) into here:

 <ItemsControl x:Name="content"/>

This is in the XAML markup

I have an On NavigatedFrom Method:

protected override void OnNavigatedFrom(NavigationEventArgs e)
{
    content.Items.Clear();
}

This successfuly removed the control, as before adding this, when I went back to the page it crashed telling me the control was already a child of an element.

here is the full pages code:

public partial class Wizard : IPartImportsSatisfiedNotification
{
    public Wizard()
    {
        InitializeComponent();
        CompositionInitializer.SatisfyImports(this);

        var controlToLoad = IsolatedStorageHelper.GetValue("control");

        if (!String.IsNullOrEmpty(controlToLoad))
        {
            CatalogService.AddXap(controlToLoad + ".xap");
        }
    else
    {
        NavigationService.Navigate(new Uri("/ServiceSelector", UriKind.Relative));
    }
}

protected override void OnNavigatedFrom(NavigationEventArgs e)
{
    content.Items.Clear();
}

[Import]
public IDeploymentCatalogService CatalogService { get; set; }

[ImportMany(AllowRecomposition = true)]
public Lazy<UserControl>[] MefModuleList { get; set; }

#region IPartImportsSatisfiedNotification Members

public void OnImportsSatisfied()
开发者_如何学C{
    MefModuleList.ToList()
        .ForEach(module =>
            content.Items.Add(module.Value)
        );
}

#endregion
}

Anyone any ideas?

Thanks,

---

A simple fix would be to avoid the whole issue by using ExportFactory rather than Lazy: Create a new instance instead of reusing the old one. Just make sure the discarded instances get GC'd instead of piling up (EDIT: The new instances are handed to you in ExportLifetimeContext instances, which mange the lifespan of the object).

What's going wrong now sounds like the old child still thinks he has a parent. Before you add him back to the container again (preferably right at the point when you remove him), you need to tell him he's now parentless. UserControl.Parent is read-only, though. Maybe call RemoveLogicalChild on the parent? I haven't tested that, but the general avenue seems worth exploring, if the ExportFactory caper doesn't float your boat.