public static bool CheckDriversLicense()

in FMLab/DriversLicenseChecker.cs [15:52]

• 20 lines of code
• 3 McCabe index (conditional complexity)

        public static bool CheckDriversLicense(long customerId)
        {
            // Use LINQ to get back to the information about the 
            // license number
            FMCustomer customer;
            QueryProvider provider = new AXQueryProvider(null);
            var customers = new QueryCollection<FMCustomer>(provider);

            // Build the query (but do not execute it)
            var query = from c in customers 
                        where c.RecId == customerId 
                        select c;

            // Execute the query:
            customer = query.FirstOrDefault();
            if (customer == null)
            {
                throw new ArgumentException
                    ("The customerId does not designate a customer");
            }

            // or, much more succinctly:
            // customer = customers.Single(c => c.RecId == customerId);

            if (string.IsNullOrEmpty(customer.DriverLicense))
            {
                // No driver's license was recorded. Veto the rental.
                return false;
            }

            // Call the DOT web service to validate the license number.
            // This is not practical for this lab, because all the service providers
            // charge for this service. Instead, just assume that any license number
            // that contains the sequence "89" is valid.
            // In the demo data, this is true for Adrian Lannin,
            // but not for Phil Spencer.
            return customer.DriverLicense.Contains("89");
        }