private void refreshCoachComboBox()
        {   // Ophalen van alle Coaches
            _coachList.Clear();
            //_selectedCoach = null;
            var coachList1 = coachController.findAllByNaam();

            foreach (Coach cch in coachList1)
            {
                _coachList.Add(cch);
                _selectedCoach = cch;
                NotifyPropertyChanged("CoachList");
            }
        }
        private void refreshCoachCombo()
        {
            // Ophalen van alle Coaches
            var coachList1 = coachController.findAllByNaam();

            foreach (Coach cch in coachList1)
            {
                coachList.Add(cch);
                CoachComboBox.SelectedItem = 0;
            }
            //coachList.Add(new Coach("Stefan de Lange","",true));
            //_selectedCoachString = "Stefan de Lange";

            NotifyPropertyChanged("CoachList");
        }