public async Task AddRegionAsync(RegionViewModel model) { var office = await _officeService.GetPostOfficeByNameAsync(model.OfficeName); if (office == null) { throw new Exception("Taki urząd pocztowy nie istnieje!"); } var region = new Region(Guid.NewGuid(), office.OfficeId, model.Name); await _regionRepo.AddRegionAsync(region); }