In this document, you’ll learn how a promotion is applied to a cart’s line items and shipping methods using adjustment lines.

What are Adjustment Lines?#

An adjustment line indicates a change to an item or a shipping method’s amount. It’s used to apply promotions or discounts on a cart.

The LineItemAdjustment data model represents changes on a line item, and the ShippingMethodAdjustment data model represents changes on a shipping method.

The amount property of the adjustment line indicates the amount to be discounted from the original amount. Also, the ID of the applied promotion is stored in the promotion_id property of the adjustment line.

---

Discountable Option#

The LineItem data model has an is_discountable property that indicates whether promotions can be applied to the line item. It’s enabled by default.

When disabled, a promotion can’t be applied to a line item. In the context of the Promotion Module, the promotion isn’t applied to the line item even if it matches its rules.

---