SL5 + MEF + PRISM + DataGrid + Edit Rows in Modal Dialog: Is InteractionRequest the Answer?

Question

I am in the process of re-writing one of our large Silverlight apps to use PRISM and the MVVM design pattern.

A very common scenario is a DataGrid in the View. Double clicking a row allows the user to edit the entity represented by the row, using a ChildWindow.

I am tempted just to capture the DoubleClick event in the code behind, create a new ChildWindow of the proper type, and set the DataContext to be DataGrid.SelectedItem.

I know that this is not the proper way to handle this scenario with PRISM and MVVM, however.

I would love advice on what is! (re: my title...it seems like InteractionRequest might be the best way to do this?)

Thanks...

EDIT: We did end up deciding to go with InteractionRequest for our solution. We almost always use "Notification" as the type and pass a new ViewModel (each ChildWindow has its own) as the Content.

Answer 1

In our case the ChildWindow view was complex enough to warrant its own viewmodel. This view isn't too closely coupled with the data grid view.

So, we have an EventTrigger attached to the data grid (we actually use Telerik's data grid) in XAML. The event trigger executes a command in the view model using InvokeCommandAction.

The command publishes an aggregated event that has the selected item as the payload. The event is picked up by the central application controller that is responsible for creating the ChildWindow view and a corresponding view model (using the event payload as the context).

I think that interaction request could potentially be used in your case, but based on my understanding the idea behind an interaction request is a very simple Ok or Yes/No interaction. You might be pushing the boundaries with a bunch of text boxes, validation, etc.