add a check with MessageBox when DataGrid is changed

Question

I have a desktop app already released (so I\'d appreciate an answer that keeps the changes and regression tests at a minimum) and I need to add a consistency check Can

Answer 1

What I've done till now is

against MVVM, because I've put the alert in the Model

The solution from @Tesseract, subclassing ObservableCollection and subscribing RemoveItem is already MVVM oriented.

What is still missing is a correct, modern way to send the alert from the ViewModel. This is where Mahapps approach would be helpful.

• Use an attached property in your Window to register your view model with the dialog sub-system.

In your XAML

Dialog:DialogParticipation.Register="{Binding}"

where the attached property DialogPartecipation will keep track of the views through a dictionary

public static class DialogParticipation
{
    private static readonly IDictionary ContextRegistrationIndex = new Dictionary

• You can instantiate DialogCoordinator directly or inject the interface IDialogCoordinator into their view model

The DialogCoordinator will match the ViewModel to the View

public class DialogCoordinator : IDialogCoordinator
{
    public static readonly IDialogCoordinator Instance = new DialogCoordinator();

through the above said attached property (the context being the view model)

var association = DialogParticipation.GetAssociation(context);

and display the dialog, invoking the appropriate method on the retrieved view: this is how, if you have multiple windows open, the dialog will display on the correct window.