WPF Caliburn.Micro：生命周期问题

Question

I have a class called AppViewModel, this class it's responsible to control the screens. AppViewModel extends my BaseConductor:

public class BaseConductor : Conductor<Screen>.Collection.OneActive
{
   ...
}

Then, I call a viewmodel (UserControl) on the constructor of AppViewModel:

        this.ActivateItem(new FirstViewModel());

On FirstViewModel , after the user clicks on a button I want to open SecondViewModel and close the FirstViewModel :

var conductor = this.Parent as IConductor;
conductor.DeactivateItem(this, true);
conductor.ActivateItem(new SecondViewModel(param));

I already tried to do this:

((IApp)this.Parent).ActivateItem(new SecondViewModel(param));
TryClose();

SecondViewModel extends my BaseScreen:

public class BaseSceen : Screen
{
   ...
}

I want to close the FirstViewModel, because on the FirstViewModel and SecondViewModel I have shortcuts. When I'm with the SecondViewModel opened I hit a shortcut, and the method that is executed it's from FirstViewModel. So, the FirstViewModel still running.

How can I close the FirstViewModel, and avoid this problem with shortcuts?

Thanks!

Answer 1

Do you really need to use Conductor<T>.Collection.OneActive ? You can just use Conductor<T> so that activating an item will automatically deactivate and close the previously active item. And also, is it required that the button/action pair reside in the FirstViewModel ? I suggest that you just put those in the AppViewModel and let it orchestrate the navigation and activation/deactivation of the two child screens.

public AppViewModel : Conductor<Screen>
{
    public void AppViewModel()
    {
        ActivateItem(new FirstViewModel());
    }

    public void ActivateSecondViewModel()
    {
        // FirstViewModel will automatically be deactivated
        // and closed since we are using plain Conductor<T>
        ActivateItem(new SecondViewModel());
    }
}

Answer 2

I found it! The shortcut event was attached to the window, not to the usercontrol. So, event when usercontrol was ended the event still "attached" to the window. Now, I added an method that is called when UserControl is Unloaded, to "deattach" the event. Bad mistake!