How to create a custom offer condition

Oscar ships with several condition models that can be used to build offers. However, occasionally a custom condition can be useful. Oscar lets you build a custom condition class and register it so that it is available for building offers.

Custom condition interface

Custom condition classes must be proxy models, subclassing Oscar’s main Condition class.

At a minimum, a custom condition must:

  • have a name attribute which with the condition name.
  • have a description attribute which describes what needs to happen to satisfy the condition (eg “basket must have 4 items”).
  • have an is_satisfied method that takes a basket instance and an offer instance and returns a boolean indicating if the condition is satisfied

It can also implement:

  • a can_apply_condition method that takes a product instance and returns a boolean depending on whether the condition is applicable to the product.
  • a consume_items method that marks basket items as consumed once the condition has been met.
  • a get_upsell_message method that returns a message for the customer, letting them know what they would need to do to qualify for this offer.
  • a is_partially_satisfied method that tests to see if the customer’s basket partially satisfies the condition (ie when you might want to show them an upsell message)

Silly example:

from oscar.apps.offer import models

class BasketOwnerCalledBarry(models.Condition):
    name = "User must be called barry"

    class Meta:
        proxy = True

    def is_satisfied(self, offer, basket):
        if not basket.owner:
            return False
        return basket.owner.first_name.lower() == 'barry'

Create condition instance

To make this condition available to be used in offers, do the following:

from oscar.apps.offer.custom import create_condition

create_condition(BasketOwnerCalledBarry)

Now you should see this condition in the dashboard when creating/updating an offer.

Deploying custom conditions

To avoid manual steps in each of your test/stage/production environments, use South’s data migrations to create conditions.