private void ComboBox_Sections_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
PersonModel ps = (PersonModel)DataContext;
SectionMethods sm = new SectionMethods();
ps.short_section_name = (sender as ComboBox).SelectedItem.ToString();
ps.id_section = sm.GetIdByShortName(ps.short_section_name);
}
