Question

(Note: I chose to not use the Navigation Framework)

I have a WizardViewModel which is linked to WizardView.
The WizardViewModel declares and instantiates a command “Next”.
It also contains a Property “ActiveSpell” of Type SpellViewModel.

The SpellViewModel contains several PageViewModels, each having a View counterpart.
The ActivePage Property (on SpellViewModel) tells the ui which view to take.

Now I have the following problem:
When I click a button to switch to the next page,
I need access to the “Next” command defined in the WizardViewModel,
but I only have access to a PageViewModel there.

I could just add a Parent property to each child ViewModel,
but I’m not sure if that is a good idea.
Or maybe there is another nicer/common way to do that.

Answer 1

You don’t need Parent property. Your view model structure is good, just look at the picture, to understand how you should bind your view model onto the view:

Next command should be implemented something like that:

public void NextExecute()
{
    ActualSpell.MoveToNextPage();
}

UPDATE:
According to your comment, Arokh, I’ve updated the post.
I think, in this case you should implement ActivateCreatePersonSpell command in WizardViewModel.This command should:

• save actual spell state
• open CreatePerson spell
• once person is created set saved spell with result of creation person

The last what you need to do is to bind ActivateCreatePersonSpell command to button on the page. I propose to use ViewModelLocator for these purposes.Look at this post for example.