Question

In my main window named (MainWindow by mistake) I have a method for getting a value once it has been triggered, this works for my usercontrols but for some reason when I attempt this on my MainWindow there are no definitions for OnStudentIDChanged.

    public static readonly DependencyProperty StudentIDProperty = DependencyProperty.Register("StudentID", typeof(String), typeof(LoginWindow), new PropertyMetadata(OnStudentIDChanged));

    public string StudentID
    {
        get { return (string)GetValue(StudentIDProperty); }
        set { SetValue(StudentIDProperty, value); }
    }

    static void OnStudentIDChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        (d as LoginWindow).OnStudentIDChanged(e); // OnStudentIDChanged no definition?
    }

Answer 1

Perhaps your intention was to cast d to MainWindow instead of LoginWindow?

static void OnStudentIDChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    (d as MainWindow).OnStudentIDChanged(e); 
}

but that is still wrong because it’s an infinite recursion (guessing from your previous post)…