public void changeCourseExecuted()
        {
            StudentsForDatagrid.Clear();

            if (SelectedCourse == null)
            {
                return;
            }

            // load datagrid with students
            using (var service = new ClassAdministrationServiceClient(new BasicHttpBinding(), new EndpointAddress(BUTEClassAdministrationClient.Properties.Resources.endpointAddress)))
            {
                Student[] students = service.ReadStudentsFromCourse(SelectedCourse.Id);

                foreach (var student in students)
                {
                    StudentsForDatagrid.Add(student);
                }
            }

            // load target course combobox
            TargetCoursePairs.Clear();
            foreach (var coursePair in CoursePairs)
            {
                if (((Course)coursePair.CourseObject).Id != SelectedCourse.Id)
                {
                    TargetCoursePairs.Add(coursePair);
                }
            }
        }
        public void changeGroupExecuted()
        {
            StudentsForDatagrid.Clear();
            if (SelectedGroup == null)
            {
                return;
            }

            // load datagrid with students
            foreach (var student in SelectedGroup.Student)
            {
                StudentsForDatagrid.Add(student);
            }

            // load target group combobox
            TargetGroupPairs.Clear();
            foreach (var groupPair in GroupsForCombobox)
            {
                if (((Group)groupPair.GroupObject).Index != SelectedGroup.Index)
                {
                    TargetGroupPairs.Add(groupPair);
                }
            }
        }