// To add a transaction
public async Task <HttpResponseMessage> PostAsync(Transaction transaction)
{
List <Customer> customers = await sqlDbHelper.GetCustomers();
// checks if that customer exists in the table
if (customers.Find(a => a.CardNumber == transaction.CardNumber) == null)
{
// if the customer does not exist, then no transaction could be made
return(Request.CreateResponse(HttpStatusCode.NotFound));
}
else
{
// if a customer exists a transaction will be created
await sqlDbHelper.AddTransaction(transaction);
return(Request.CreateResponse(HttpStatusCode.OK, "Created!"));
}
}