//post request to add an airline public async Task <HttpResponseMessage> PostAsync(Airline airline) { List <Airline> airlines = await sqlDbHelper.GetAirlines(); //to check if there's no airline with the same code in the table if (airlines.Find(a => a.Code == airline.Code) == null) { //in case it doesn't exist then the airline will be added and ok status code is returned await sqlDbHelper.AddAirline(airline); return(Request.CreateResponse(HttpStatusCode.OK, "Created")); } else { // in case an airline with the same code exists then it won't be added and cannot be created message is returned return(Request.CreateResponse(HttpStatusCode.OK, "Cannot be created!")); } }