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c#.netwpfmvvminotifypropertychanged

In MVVM should the ViewModel or Model implement INotifyPropertyChanged?

Most MVVM examples I have worked through have had the Model implement INotifyPropertyChanged, but in Josh Smith's CommandSink example the ViewModel implements INotifyPropertyChanged.

I'm still cognitively putting together the MVVM concepts, so I don't know if:

  • You have to put the INotifyPropertyChanged in the ViewModel to get CommandSink to work
  • This is just an aberration of the norm and it doesn't really matter
  • You should always have the Model implement INotifyPropertyChanged and this is just a mistake which would be corrected if this were developed from a code example to an application

What have been others' experiences on MVVM projects you have worked on?

Solution

  • I'd say quite the opposite, I always put my INotifyPropertyChanged on my ViewModel - you really don't want to be polluting your model with a fairly WPF specific feature like INotifyPropertyChanged, that stuff should sit in the ViewModel.

    I'm sure others would disagree, but that's the way I work.