public string StockPrice(string pubicKey, string hash, List <string> stockCodes) { if (string.IsNullOrWhiteSpace(pubicKey) || string.IsNullOrWhiteSpace(hash) || !_apiHelper.ValidateRequest(pubicKey, hash, stockCodes)) { throw new InvalidOperationException(_invalidRequest); } return(JsonConvert.SerializeObject(_stockPrice.GetStockPrices(stockCodes))); }