protected override bool isValid(out string exceptionMessage) { if (name.Length == 0) { return makeExceptionMessage (out exceptionMessage, "The name of the city is invalid"); } if (!validCountry (country, out exceptionMessage)) { return false; } CountryRequest cor = new CountryRequest (); string countryName = cor.fetchFromID (country) [0].name; CityRequest cr = new CityRequest (); if (cr.fetchFromNameAndCountry (name, countryName).Count () != 0) { return makeExceptionMessage (out exceptionMessage, "The name of the city already exists for a city in the country " + countryName); } return makeExceptionMessage(out exceptionMessage); }