private void AddNewSubject(object sender, RoutedEventArgs e) { var addDialog = new Dialogs.AddModifySubjectDialog(_teacherRepository.GetAllTeachers().ToList()); addDialog.ShowDialog(); if (!addDialog.IsSelected) { return; } int insertedId = -1; try { insertedId = _subjectRepository.AddNewSubject(addDialog.SelectedSubjectName, addDialog.SelectedTeacher.TeacherId, addDialog.SelectedSubjectDescription); } catch (SqlException ex) { if (ex.Number == 50005) { MessageBox.Show(ex.Message); return; } } _displayedSubjects.Add(new Subject() { SubjectId = insertedId, SubjectDescription = addDialog.SelectedSubjectDescription, TeacherId = addDialog.SelectedTeacher.TeacherId, Name = addDialog.SelectedSubjectName }); SubjectList.Items.Refresh(); AwailableSubjects.Items.Refresh(); }