Question

I am trying to create a module with PRISM and right now I set the DataContext inside the View which means I can only use a Parameterless constructor, but that means I cant use dependency injection (I use Unity) in the constructor which I would like

If it is possible I would like neither the view or the vm to know each other and want to use something like

private void RegisterServices()
{
    var employeeViewModel = new EmployeeViewModel();

    _container.RegisterType<IEmployeeViewModel, EmployeeViewModel>();
    _container.RegisterType<EmployeeView>();

    EmployeeView.Datacontext = employeeViewModel;
}

Which I would register in the EmployeeModule

Is this possible or should I use code behind?

Answer 1

You may pass the interface of ViewModel to the View in the constructor. This way, View only knows the interface of ViewModel and ViewModel knows nothing about the View.

Ex.

public class EmployeeView : UserControl
{
    public EmployeeView(IEmployeeViewModel vm)
    {
         this.DataContext = vm; //// better to set the ViewModel in the Loaded method
    }
}

Refer to this blog post for multiple approaches of MVVM instantiation.