I thought this would be simple but can't find any good examples.

public Class BookVm : ImplementsPropertyChanged
{
    public int BookId {get;set;}
    private bool _favorite;
    public bool Favorite
    { 
        get { return _favorite; }
        set {
                _favorite = value;
                OnPropertyChanged("Favorite");
               MyDbContext.SaveChanges() // this does not work
        }
    }

Then in my XAML bound to Book

<CheckBox Content="Favorite" IsChecked="{Binding Favorite}" />

How and when do I call SaveChanges() on my DatabaseContext?

I don't want to implement a save button. If I intercept the PropertyChange event and call SaveChanges, nothing seems to happen. My object is modified in memory but the database does not see a change.

My BookVm class is created on application startup like so:

        foreach (var book in MyDbContext.Books)
            Books.Add(book);

Where Books is an ObservableCollection<Book> in my MainWindowVm