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Version: 4.0

How to use a custom promotion adjuster

Every time an order is updated, its eligible promotions might not be valid anymore; for example, this could happen if a promotion is tight to a specific order total threshold, and this value changes within the update. In the same way, changing the order could make it eligible for new promotions.

In this guide, we'll see how to use our custom logic to recalculate adjustments every time an order is updated.

In Solidus, this behavior is encapsulated in the Spree::Promotion::OrderAdjustmentsRecalculator, class, which is called every time the order is updated. This class iterates over all existing promotion adjustments and recalculates their amount and eligibility.


Please, keep in mind that promotion adjustments are handled before taxes are calculated, such that taxes always respect promotions.

We'll now see how to use our own class instead of the one provided by Solidus.

First of all, let's declare which promotion adjuster class we want to use, with the corresponding configuration:

Spree.config do |config|
# ...
config.promotion_adjuster_class = 'MyStore::PromotionAdjuster'

Lastly, let's create our custom class, which implements the same interface of the original promotion adjuster class provided by Solidus:

module MyStore
class PromotionAdjuster
def initialize(order)
@order = order

def call
# Your custom logic here.

Keep in mind that if you define your class as:

class PromotionAdjuster < ::Spree::Promotion::OrderAdjustmentsRecalculator

you will be able to use super in its methods to execute parts of the original class provided by Solidus.