How do I subscribe to PropertyChanged event in my ViewModel?

Question

I have core functionality encapsulated in ViewModelBase

Now I want to see when PropertyChanged event was raised by ViewModelBase and act on it. For example, when one property was changed on ViewModelBase - I want to change property on my ViewModel

How do I achieve this?

public class MaintainGroupViewModel : BaseViewModel<MEMGroup>     {   public abstract class BaseViewModel<T> : NotificationObject, INavigationAware         where T : Entity     { 

Answer 1

Usually I use register to the PropertyChanged event in the class Constructor

public MyViewModel() {     this.PropertyChanged += MyViewModel_PropertyChanged; } 

and my PropertyChanged event handler looks like this:

void MyViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e) {     switch (e.PropertyName)     {         case "SomeProperty":             // Do something             break;     } } 

Answer 2

I am concerned that you're effectively doing a 'manual binding' (bad) for a property in a derived class to a value on the base class (also bad). The whole point of using inheritance is that the derived class can access things in the base class. Use a protected modifier to indicate things should only be accessible to derived classes.

I would suggest this (potentially) more correct method:

Base class:

protected virtual void OnMyValueChanged() { } 

Derived class:

protected override void OnMyValueChanged() { /* respond here */ } 

Really, subscribing to an event in the base class of the very class you're writing just seems incredibly backwards - what's the point of using inheritance over composition if you're going to compose yourself around yourself? You're literally asking an object to tell itself when something happens. A method call is what you should use for that.

In terms of "when one property was changed on ViewModelBase - I want to change property on my ViewModel", ... they are the same object!