Prism 4: Unloading view from Region?

Question

How do I unload a view from a Prism Region?

I am writing a WPF Prism app with a Ribbon control in the Shell. The Ribbon's Home tab contains a region, RibbonHomeTabRegion, into which one of my modules (call it ModuleA) loads a RibbonGroup. That works fine.

When the user navigates away from ModuleA, the RibbonGroup needs to be unloaded from the RibbonHomeTabRegion. I am not replacing the RibbonGroup with another view--the region should be empty.

EDIT: I have rewritten this part of the question:

When I try to remove the view, I get an error message that "The region does not contain the specified view." So, I wrote the following code to delete whatever view is in the region:

// Get the regions views
var regionManager = ServiceLocator.Current.GetInstance<IRegionManager>();
var ribbonHomeTabRegion = regionManager.Regions["RibbonHomeTabRegion"];
var views = ribbonHomeTabRegion.Views;

// Unload the views
foreach (var view in views)
{
    ribbonHomeTabRegion.Remove(view);
}

I am still getting the same error, which tells me there is something pretty basic that I am doing incorrectly.

Can anyone point me in the right direction? Thanks for your help.

Answer 1

I found my answer, although I can't say I fully understand it. I had used IRegionManager.RequestNavigate() to inject the RibbonGroup into the Ribbon's Home tab, like this:

// Load RibbonGroup into Navigator pane
var noteListNavigator = new Uri("NoteListRibbonGroup", UriKind.Relative);
regionManager.RequestNavigate("RibbonHomeTabRegion", noteListNavigator);

I changed the code to inject the view by Registering it with the region, like this:

// Load Ribbon Group into Home tab
regionManager.RegisterViewWithRegion("RibbonHomeTabRegion", typeof(NoteListRibbonGroup));

Now I can remove the RibbonGroup using this code:

if(ribbonHomeTabRegion.Views.Contains(this))
{
    ribbonHomeTabRegion.Remove(this);
}

So, how you inject the view apparently matters. If you want to be able to remove the view, inject by registration with the Region Manager

Answer 2

StockTraderRI Example Project by Microsoft contains the following example of removing views from region in ViewModel.

private void RemoveOrdersView()
{
    IRegion region = this._regionManager.Regions[RegionNames.ActionRegion];

    object ordersView = region.GetView("OrdersView");
    if (ordersView != null)
    {
        region.Remove(ordersView);
    }
}