c# - How can I combine MVVM and Dependency Injection in a WPF app?

Question

Can you please give an example of how you would use (your favorite) DI framework to wire MVVM View Models for a WPF app?

Will you create a strongly-connected hierarchy of View Models (like where every nested control's ViewModel is a property on a parent's ViewModel and you bind it to nested control's DataContext in XAML) or you would use some kind of even-more-abstract ""View Model" Manager", which maintains some weakly-connected hierarchy... like in CAB, maybe?

Answer 1

If a view model can only exist in conjunction with another, I create a strong relationship. That is the owning view model will have a direct reference to one or more of the dependent view models. If, on the other hand, a view model should be able to exist with or without another, I take a loosely-coupled approach where they communicate via an event bus.

In terms of using DI with MVVM, absolutely you can combine the two. It's as simple as:

public class MyViewModel
{
    private readonly IMyDependency _myDependency;

    public MyViewModel(IMyDependency myDependency)
    {
        _myDependency = myDependency;
    }
}

Note, however, that this assumes a "view model first" approach to MVVM, which has its drawbacks.