Django SHOP Payer Backend

Django SHOP payment backend for Payer. Uses python-payer-api for interacting with the API.

Installation

pip install django-shop-payer-backend

Add to installed apps

INSTALLED_APPS = [
    ...
    'polymorphic',
    'shop'
    'shop.addressmodel',
    'django_shop_payer_backend',
    ...
]

Configure one ore more payment backends

SHOP_PAYMENT_BACKENDS = [
    'django_shop_payer_backend.backends.PayerCreditCardPaymentBackend',
    'django_shop_payer_backend.backends.PayerBankPaymentBackend',
    'django_shop_payer_backend.backends.PayerInvoicePaymentBackend',
    'django_shop_payer_backend.backends.PayerPhonePaymentBackend',
]

You could also use the GenericPayerBackend in order to let the user choose payment method after being redirected to Payer, or define a subclass of your own, listing a custom set of methods in the payment_methods property. This might be a good option if you are using the Payer backend along with other backends such as Paypal etc.

Configuration

Add your keys to settings.py

SHOP_PAYER_BACKEND_AGENT_ID = "AGENT_ID"
SHOP_PAYER_BACKEND_ID1 = "6866ef97a972ba3a2c6ff8bb2812981054770162"
SHOP_PAYER_BACKEND_ID2 = "1388ac756f07b0dda2961436ba8596c7b7995e94"

The following settings are optional

# Used for white/blacklisting callback IPs
SHOP_PAYER_BACKEND_IP_WHITELIST = ["192.168.0.1"]
SHOP_PAYER_BACKEND_IP_BLACKLIST = ["10.0.1.1"] 
# Used for suppliying an address model
SHOP_PAYER_BACKEND_ADDRESS_HANDLER = 'project.app.path.to.address_model_callback'

SHOP_PAYER_BACKEND_HIDE_DETAILS = False     # Hide order details during payment
SHOP_PAYER_BACKEND_DEBUG_MODE = 'verbose'   # 'silent', 'brief'
SHOP_PAYER_BACKEND_TEST_MODE = True

Considerations

Due to the fact that django SHOP by default does not store any relation between the Order model and the AddressModel model there is no good way for payment backends to determine the shipping/billing address for a given order. For some backends this might not be an issue, but in this case Payer expects to address data in the order details.

django-shop-payer-backend tries to tackle by determining the order (billing) address using the following strategy:

1. Try to fetch AddressModel from current user (if user.is_authenticated()).
2. Try to load an AddressModel using a callback supplied in the SHOP_PAYER_BACKEND_ADDRESS_HANDLER setting.
3. Try to extract address details from order.billing_address_text by reverse parsing the address template used by django SHOP.
4. Let you override/complete the data returned using the above methods using the populate_buyer_details_dict signal.

This has two implications:

1. For non-authenticated users it is simply not possible get an AddressModel object using the default setup. In this case a reverse parsing of the address template string django SHOP uses to store the textual address representation on the Order object. Due to the somewhat fragile nature of this parsing method, you should take extreme precautions when modifying the SHOP_ADDRESS_TEMPLATE setting. For the parser to function it is recommended that you use some form identifying "key" to identify each keyword (as with "Name:"" etc. in the default pattern). Patterns such as %(name)s, %(address)s,[...] will likely fail as there is nothing differentiating the name and address keywords in the string format, and alas the regexp will not be able to identify the keywords correctly.
2. Fields supported by the Payer API that do not have an obvious counterpart on the AddressModel model (e.g. email, phone, organisation, etc.) will unsurprisingly not be included in the PayerBuyerDetails data using the default settings. To make sure they are included, use the methods described in the Extensibility section below.

The way to tackle both of the issues outlined above, is probably to add a foreign key to AddressModel on Order and store the object used when setting order.billing_address_text. That way you could add a address model callback handler (described below), which will let you return that (or any other) object to the backend.

Extensibility

Let's say you have a custom address model based on shop.addressmodel.models.Address which adds the field company. Naturally you would want this data sent to Payer as well, in order to have it appear on invoices etc. To accomplish that, add a receiver for the populate_buyer_details_dict signal and update the buyer details dict like so:

from django_shop_payer_backend.helper import populate_buyer_details_dict
from django.dispatch import receiver

@receiver(populate_buyer_details_dict)
def add_additional_buyer_details(sender, **kwargs):

    buyer_details_dict = kwargs.get('buyer_details_dict', None)
    user = kwargs.get('user', None)
    address = kwargs.get('address', None)
    order = kwargs.get('order', None)

    buyer_details_dict.update({
        'organisation': address.company,
    })

There is a similar signal, populate_order_item_dict, for order items, allowing you to modify the data that before the PayerOrderItem object is initialized. This can be useful for example if your Product model has a field holding VAT percentages, in which case you could inject that value using this method.

Another option for supplying an address to the backend is to implement and address callback handler, and return an AddressModel object. This is a good option if you are using a custom Order model that has foreign keys to the AddressModel. In that case, you can implement a callback something along the lines of the following:

def address_model_callback(*args, **kwargs):

    address = kwargs.get('address', None)
    order = kwargs.get('order', None)

    if address is None and order is not None:
        try:
            address = order.billing_address
        except Exception:
            pass

    return address

And add the following to settings.py:

SHOP_PAYER_BACKEND_ADDRESS_HANDLER = 'project.app.path.to.address_model_callback'