django-getpaid 1.3.0

Multi-broker payment processor for Django
django-getpaid is carefully designed multi-broker payment processor for Django apps. The main advantages of this django application is:

- instead of only one payment broker, you can use multiple payment brokers in your application, what is wise considering ane single payment broker downtime,
- payment brokers have a flexible architecture each one based on a django application structure (they can introduce own logic, views, urls, models),
- support to asynchronous payment status change workflow (which is required by most brokers and is architecturally correct for production use),
- support for multiple payments currency at the same time,
- uses just a minimal assumption on your code, that you will have any kind of order model class.

The basic usage is to connect you order model class with django-getpaid. Because of using advanced AbstractMixin, Payment model class uses real ForeignKey to your order class model, so it avoids messy django content_type relations.

This app was written because still there is not a single reliable or simple to use payment processor. There are many payments related projects out there like Satchmo, python-payflowpro, django-authorizenet, mamona, django-paypal, django-payme, but none of them are satisfying. Mamona project was the most interesting payment app out there (because of general conception), but still has got some serious architectural pitfalls. Therefore django-getpaid in the basic stage was aimed to be a next version of mamona. Unfortunately plenty of architectural decisions of mamona author caused, that django-getpaid has been started as a separate project, while still borrowing a lot of great ideas from mamona, like e.g. using AbstractMixin, dynamic model and urls loading, etc. Thanks mamona!

Disclaimer: this project has nothing in common with getpaid plone project. It is mostly based on mamona project.

Payment workflow integration

With few simple steps you will easily integrate your project with django-getpaid. This module is shipped with very well documented django-getpaid test project which can be found with module source code. Please refer to this code for implementation details.

Prepare your order model

Required

First of all you need a model that will represent an order in you application. It does not matter how complicated the model is or what fields it provides, is it single item order, or multiple items order. Let's take an example from test project::

from django.core.urlresolvers import reverse
from django.db import models
import getpaid

class Order(models.Model):
 name = models.CharField(max_length=100)
 total = models.DecimalField(decimal_places=2, max_digits=8, default=0)
 currency = models.CharField(max_length=3, default='EUR')
 status = models.CharField(max_length=1, blank=True, default='W', choices=(('W', 'Waiting for payment'),
 ('P', 'Payment complete')))
 def get_absolute_url(self):
 return reverse('order_detail', kwargs={'pk': self.pk})

 def __unicode__(self):
 return self.name


getpaid.register_to_payment(Order, unique=False, related_name='payments')

First of all class name is not important at all. You register a model with register_to_payment method.

You can add some kwargs that are basically used for ForeignKey kwargs. In this example whe allow of creating multiple payments for one order, and naming One-To-Many relation.

There are two important things on that model. In fact two methods are required to be present in order class. The first one is __unicode__ method as this will be used in few places as a fallback for generating order description. The second one is get_absolute_url method which should return an URL of order object. It is used again as a fallback for some final redirections after payment success of failure (if you do not provide otherwise).

The second important thing that it actually don't mather if you even store total in database, or just can sum it up from some items. You will see why, in further sections.

Prepare payment form for order

Required

Your application after some custom workflow just created an order object. That's fine. We now want to get paid for that order. So lets take a look on a view for creating a payment for an order::

from django.views.generic.detail import DetailView
from getpaid.forms import PaymentMethodForm
from getpaid_test_project.orders.models import Order

class OrderView(DetailView):
 model=Order

 def get_context_data(self, **kwargs):
 context = super(OrderView, self).get_context_data(**kwargs)
 context['payment_form'] = PaymentMethodForm(self.object.currency, initial={'order': self.object})
 return context


Here we get a PaymentMethodForm object, that is parametrised with currency type. This is an important thing, because this form will display you only payments method that are suitable for a given order currency.

PaymentMethodForm provides two fields: HiddenInput with order_id and ChoiceField with backend name. This is how you use it in template::

< form action="{% url getpaid-new-payment currency=object.currency %}" method="post" >
 {% csrf_token %}
 {{ payment_form.as_p }}
 < input type="submit" value="Continue" >
< /form >


Action URL of form should point on named link getpaid-new-payment that requires currency code argument. This form will redirect client from order view directly to page of payment broker.

Filling necessary payment data

Required

Because the idea of whole module is that it should be loosely coupled, there is this convention that it does not require any structure of your order model. But still it need to know some transaction details of your order. For that django signals is used. djang-getpaid while generating gateway redirect url will emit to your application a getpaid.signals.new_payment_query signal. Here is the signal declaration::

new_payment_query = Signal(providing_args=['order', 'payment'])
new_payment_query.__doc__ = """
Sent to ask for filling Payment object with additional data:
 payment.amount: total amount of an order
 payment.currency: amount currency
This data cannot be filled by ``getpaid`` because it is Order structure
agnostic. After filling values just return. Saving is done outside signal.
"""


Your code should have some signal listeners, that will fill payment object with required information::

from getpaid import signals

def new_payment_query_listener(sender, order=None, payment=None, **kwargs):
 """
 Here we fill only two obligatory fields of payment, and leave signal handler
 """
 payment.amount = order.total
 payment.currency = order.currency


signals.new_payment_query.connect(new_payment_query_listener)

So this is a little piece of logic that you need to provide to map your order to payment object. As you can see you can do all fancy stuff here to get order total value and currency code.

.. note::

If you don't know where to put your listeners code, we recommend to put it in ``listeners.py`` file and then add a line ``import listeners`` to the end of you ``models.py`` file. Both files (``listeners.py`` and ``models.py``) should be placed in on of your app (possibly an app related to order model).

Handling changes of payment status

Required

Signals are also used to inform you that some particular payment just change status. In this case you will use getpaid.signals.payment_status_changed signal which is defined as::

payment_status_changed = Signal(providing_args=['old_status', 'new_status'])
payment_status_changed.__doc__ = """Sent when Payment status changes."""

example code that handles status change::

from getpaid import signals

def payment_status_changed_listener(sender, instance, old_status, new_status, **kwargs):
 """
 Here we will actually do something, when payment is accepted.
 E.g. lets change an order status.
 """
 if old_status != 'paid' and new_status == 'paid':
 # Ensures that we process order only one
 instance.order.status = 'P'
 instance.order.save()

signals.payment_status_changed.connect(payment_status_changed_listener)


For example when payment changes status from any non 'paid' to 'paid' status, that means that all necessary amount was verified by your payment broker. You can now access payment.order object and do some stuff here.

Handling new payment creation

Optional


For some reasons (e.g. for KPI benchmarking) it can be important to you how many and which payments were made. For that reason you can handle getpaid.signals.new_payment signal defined as::

new_payment = Signal(providing_args=['order', 'payment'])
new_payment.__doc__ = """Sent after creating new payment."""


.. note::

This method will enable you to make on-line KPI processing. For batch processing you can just query a database for Payment model as well.

Setup your payment backends

Required


Please be sure to read carefully section :doc:backends for information of how to configure particular backends. They will probably not work out of the box without providing some account keys or other credentials.

last updated on:
July 20th, 2012, 15:35 GMT
price:
FREE!
developed by:
Krzysztof Dorosz
homepage:
github.com
license type:
MIT/X Consortium License 
category:
ROOT \ Internet \ Django Plugins

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