How to use custom logic to calculate return refunds

We'll see how to customize the refund amount customers get when they perform a return. Solidus performs full-amount refunds by default, but we can change it easily.

We need a completed order, with payments captured and shipments delivered. Go through the checkout process and fulfill those conditions in the admin or console:

order = Spree::Order.find_by_number('R723438584')
order.payments.map(&:capture!)
order.shipments.map(&:ship!)

You can go to the admin panel and check how the total amount for each inventory unit is presented by default when creating a new RMA for that order. That's the logic done by the default return calculator, which is configured in the return item model.

Sometimes, though, stores need a stricter policy. Imagine that the full refund is only granted during the first week after placing the order. During the second week, there's a 25% penalty; beyond that, only 50% of the item's price is refunded.

We can create our custom refund calculator accounting for those requirements while we can still lean on the default implementation:

app/services/amazing_store/calculator/returns/with_penalty.rb

# frozen_string_literal: true

module AmazingStore
  module Calculator
    module Returns
      class WithPenalty < Spree::Calculator::Returns::DefaultRefundAmount
        def compute(return_item)
          default = super
          case days_since_order(return_item)
          when 0..7
            default
          when 8..14
            default * 0.75
          else
            default * 0.5
          end
        end

        private

        def days_since_order(return_item)
          (Date.today - return_item.inventory_unit.order.created_at.to_date).to_i
        end
      end
    end
  end
end

We need to configure the returns item model to enable our calculator. Let's leverage the Solidus' initializer for that:

config/initializers/spree.rb

# ...
Rails.application.config.to_prepare do
  ::Spree::ReturnItem.refund_amount_calculator = AmazingStore::Calculator::Returns::WithPenalty
end
# ...

That's it! Restart the server and check it out yourself. You might want to manually update the order's :created_at field to test the different possible situations.