protected bool ValidAddress(BaseAddressDto address) { var stateId = address.StateId; var cityId = address.CityId; if (!_databaseProvider.StateExists(stateId)) { ModelState.AddModelError("Not Found Entity", "There is no State with the specified Id"); return(false); } if (cityId.HasValue && cityId != 0) { if (!_databaseProvider.CityExists((int)cityId)) { ModelState.AddModelError("Not Found Entity", "There is no City with the specified Id"); return(false); } if (!_databaseProvider.CityExistsInState(stateId, (int)cityId)) { ModelState.AddModelError("Wrong Entity", "The City input Id does not correspond with the State input Id"); return(false); } } return(true); }