WPF MVVM dialog example

Question

Does anyone have any examples of showing a window dialog using MVVM (Prism)? - for example a configuration settings window when a command is executed.

All of the exa

Answer 1

As I understood your comment above, the question is not so much about showing the dialogs as about hiding them. There are two ways to solve this problem:

1. Use standard dialog window to implement the view. This would require to have a loosely coupled way of communication between View and ViewModel so that ViewModel can notify the View that it's ok to close without having a reference to a view.

   There are multiple frameworks exist that would allow to do it - Prism's event aggregators would be one of them. In this scenario View would subscribe to an event (say, MyDialogResultValidated), and on receiving the event it would set the DialogResult accrodingly. ViewModel (in its SaveCommand) would fire the event if validation was successful.

2. Don't use standard dialog window to implement the view. This would require to have an overlay that would effectively emulate modality.

   In this scenario the Visibility of the View and of the overlay will be bound ViewModel's IsVisible property that would be set accordingly by SaveCommand implementation, or whenever ViewModel needs to show the View.

The first approach would require having a bit of code in code-behind, requires adding global event(s), and (arguably) is less MVVM-ish. The second approach would require implementing (or using someone else's implementation) of the overlay, but won't require having any code in code-behind, won't require having global event(s), and is (arguable) more MVVM-ish.