Popup window in Silverlight 4 and Prism - silverlight-4.0

Question

In Silverlight and PRISM, what is the good way to open a popup child window which is in one Module by passing a parameter from a ViewModel in different Module.

Answer 1

Create a common interface/class known to both module, called IChildWindowService, register the IChildWindowServe/ChildWindowService in the bootstrapper.
//Highly simplified version
//Can be improved by window reuse, parameter options, stronger eventing
public class ChildWindowService : IChildWindowService
{
public ChildWindowService(IServiceLocator container)
{
_container = container;
}
public void Show<TViewModel>(TViewModel viewModel = null, Action<TViewModel, bool?> callBack = null) where TViewModel is IViewModel
{
var viewName = typeof(TViewModel).Name.Replace("Model", string.Empty);
// In bootstrapper register all instances of IView or register each view one by one
var view = _container.GetInstance<IView>(viewName);
viewModel = viewModel ?? _container.GetInstance<TViewModel>();
view.DataContext = viewModel;
var window = new ChildWindow();
window.Content = view;
var handler = (s,e) => { window.Close(); }
viewModel.RequestClose += handler;
view.Closed += (s,e) => { viewModel.RequestClose -= handler; }
// In silverlight all windows show as Modal, if you are using a third party you can make a decision here
window.Show();
}
}
Create a common CompositePresentationEvent, this event will pass the parameters from point a to point b
public class OpenChildWindowWithParameters : CompositePresentationEvent<ParamEventArgs>{}
The ViewModel in Module A raises the Event.
The Controller in Module B registers and reacts to the Event.
The Controller in Module B takes the child window service as a dependency.
When the event is raised the Controller will create the VM in Module B and pass the parameters to it, from the event, it will also use the Service to display a ChildWindow.