Is it okay to declare the view model as a static resource in a view?

Question

Hi,

When writing a MVVM WPF app, there's always a point where the view model has to be set to as the data context of the view. For me, usually that's in code. But I realized that if I declare the view model as a static resource inside the xaml and set the binding there, I don't need to do it in code anymore. This means I don't have to coordinate the view and the viewmodel in a third class somewhere, like in the App.

Is it acceptable to do this?

Thanks!

Answer 1

I'd say so. It sort of implies specific knowledge of the ViewModel from the View, but you have to set it somehow and I like the codebehindless approach here.

If you are using dependency injection this would not be appropriate, but if you aren't I'd stick with this approach.

Answer 2

Acceptable, yes, but if you are using PRISM, or DI of any sort, then it would make more sense to resolve it from the container and then set the datacontext either in code, or using a markup extension, depending on your exact solution.

Answer 3

If you want to use Dependency Injection (DI) in the View-First approach try ViewModel locator pattern:

public static class ViewModelLocator
{
  public static MainWindowViewModel MainWindowViewModel
  {
    get 
    {
      return ObjectFactory.GetInstance<MainWindowViewModel>(); 
    }
  }
};

and WPF code:

<Window 
    ...
    DataContext="{x:Static Services:ViewModelLocator.MainWindowViewModel}"
    >