Django view logic for payment processing

As with the index() method, we first initialize the same variables as, ultimately, we'll be sending results to the same template for rendering:

def payments(request) :
    loan         = Loan()
    amtPaid      = 0.00
    amtDue       = 0.00
    message      = ''
    borrower     = None
    borrowerKey  = None
    borrowerName = ''
    overpayment  = 0.00

We then initialize payments as a list with a single blank Payment instance:

    payment  = Payment()
    payments = [payment.populate()]

Next, in a similar manner to the index() method, we get instances of domain service classes representing users and loans. With the user domain service, we retrieve a list of borrower keys and names:

    config   = Config()
    userSvc  = UserService(config, 'User')
    loanSvc  = LoanService(config, 'Loan')
    borrowers = userSvc.fetchBorrowerKeysAndNames()

We then check to see if the HTTP request method was POST. If so, we check...