129 lines
4.1 KiB
Plaintext
129 lines
4.1 KiB
Plaintext
---
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sidebar_label: "Promotions Adjustments"
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---
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export const metadata = {
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title: `Promotions Adjustments in Carts`,
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}
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# {metadata.title}
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In this document, you’ll learn how a promotion is applied to a cart’s line items and shipping methods using adjustment lines.
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## What are Adjustment Lines?
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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.
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The [LineItemAdjustment](/references/cart/models/LineItemAdjustment) data model represents changes on a line item, and the [ShippingMethodAdjustment](/references/cart/models/ShippingMethodAdjustment) data model represents changes on a shipping method.
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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.
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---
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## Discountable Option
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The [LineItem](/references/cart/models/LineItem) data model has an `is_discountable` property that indicates whether promotions can be applied to the line item. It’s enabled by default.
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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.
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---
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## Promotion Actions
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When using the Cart and Promotion modules together, such as in the Medusa application, use the [computeActions method of the Promotion Module’s main service](/references/promotion/computeActions). It retrieves the actions of line items and shipping methods.
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<Note>
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Learn more about actions in the [Promotion Module’s documentation](../../promotion/actions/page.mdx).
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</Note>
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For example:
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```ts collapsibleLines="1-8" expandButtonLabel="Show Imports"
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import {
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ComputeActionAdjustmentLine,
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ComputeActionItemLine,
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ComputeActionShippingLine,
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// ...
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} from "@medusajs/framework/types"
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// retrieve the cart
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const cart = await cartModuleService.retrieveCart("cart_123", {
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relations: [
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"items.adjustments",
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"shipping_methods.adjustments",
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],
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})
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// retrieve line item adjustments
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const lineItemAdjustments: ComputeActionItemLine[] = []
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cart.items.forEach((item) => {
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const filteredAdjustments = item.adjustments?.filter(
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(adjustment) => adjustment.code !== undefined
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) as unknown as ComputeActionAdjustmentLine[]
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if (filteredAdjustments.length) {
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lineItemAdjustments.push({
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...item,
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adjustments: filteredAdjustments,
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})
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}
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})
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// retrieve shipping method adjustments
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const shippingMethodAdjustments: ComputeActionShippingLine[] =
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[]
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cart.shipping_methods.forEach((shippingMethod) => {
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const filteredAdjustments =
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shippingMethod.adjustments?.filter(
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(adjustment) => adjustment.code !== undefined
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) as unknown as ComputeActionAdjustmentLine[]
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if (filteredAdjustments.length) {
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shippingMethodAdjustments.push({
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...shippingMethod,
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adjustments: filteredAdjustments,
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})
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}
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})
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// compute actions
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const actions = await promotionModuleService.computeActions(
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["promo_123"],
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{
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items: lineItemAdjustments,
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shipping_methods: shippingMethodAdjustments,
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}
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)
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```
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The `computeActions` method accepts the existing adjustments of line items and shipping methods to compute the actions accurately.
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Then, use the returned `addItemAdjustment` and `addShippingMethodAdjustment` actions to set the cart’s line item and the shipping method’s adjustments.
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```ts collapsibleLines="1-8" expandButtonLabel="Show Imports"
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import {
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AddItemAdjustmentAction,
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AddShippingMethodAdjustment,
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// ...
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} from "@medusajs/framework/types"
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// ...
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await cartModuleService.setLineItemAdjustments(
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cart.id,
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actions.filter(
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(action) => action.action === "addItemAdjustment"
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) as AddItemAdjustmentAction[]
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)
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await cartModuleService.setShippingMethodAdjustments(
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cart.id,
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actions.filter(
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(action) =>
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action.action === "addShippingMethodAdjustment"
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) as AddShippingMethodAdjustment[]
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)
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``` |