public void Save()
 {
     if (CheckData())
     {
         VolunteerService volunteerService = new VolunteerService();
         if ((this.DataContext as VolunteerEntity).Id == -1 && !CheckDoppione())
         {
             if (volunteerService.Add(this.DataContext as VolunteerEntity) == 0)
             {
                 MessageBox.Show("Salvato!");
                 this.DataContext = new VolunteerEntity();
             }
             else
             {
                 MessageBox.Show("Errore durante il salvataggio!");
             }
         }
         else
         {
             if (volunteerService.Update(this.DataContext as VolunteerEntity) == 0)
             {
                 MessageBox.Show("Salvato!");
             }
             else
             {
                 MessageBox.Show("Errore durante il salvataggio!");
             }
         }
     }
 }