medusajs/medusa · error · MedusaError

"items" should be present as an array in the context to comp

Error message

"items" should be present as an array in the context to compute actions

What it means

computeActions for a buy-get promotion requires the computation context to contain an 'items' array (ComputeActionItemLine[]). isValidPromotionContext throws INVALID_DATA when itemsContext is null/undefined, because buy-get rules (buy X get Y) cannot be evaluated without line items.

Source

Thrown at packages/modules/promotion/src/utils/compute-actions/buy-get.ts:33

import { areRulesValidForContext } from "../validations"
import { computeActionForBudgetExceeded } from "./usage"
import { Promotion } from "@models"

export type EligibleItem = {
  item_id: string
  quantity: BigNumberInput
}

function sortByPrice(a: ComputeActionItemLine, b: ComputeActionItemLine) {
  return MathBN.lt(a.subtotal, b.subtotal) ? 1 : -1
}

function isValidPromotionContext(
  promotion: PromotionTypes.PromotionDTO | InferEntityType<typeof Promotion>,
  itemsContext: ComputeActionItemLine[]
): boolean {
  if (!itemsContext) {
    throw new MedusaError(
      MedusaError.Types.INVALID_DATA,
      `"items" should be present as an array in the context to compute actions`
    )
  }

  if (!itemsContext?.length) {
    return false
  }

  const minimumBuyQuantity = MathBN.convert(
    promotion.application_method?.buy_rules_min_quantity ?? 0
  )

  if (
    MathBN.lte(minimumBuyQuantity, 0) ||
    !promotion.application_method?.buy_rules?.length
  ) {
    return false

View on GitHub (pinned to 5e06e544a2)

Solutions

1. Populate context.items with the cart's line items mapped to ComputeActionItemLine (id, quantity, unit_price, etc.) before calling computeActions
2. If computing only shipping adjustments, ensure the buy-get promotion code is not passed in the promotionCodes array
3. Load the cart via CartModule and transform its items into the expected shape

Example fix

// before
await promotionModule.computeActions(["BUYGET_CODE"], {
  shipping_methods: [...],
})

// after
await promotionModule.computeActions(["BUYGET_CODE"], {
  items: cart.items.map((i) => ({
    id: i.id,
    quantity: i.quantity,
    unit_price: i.unit_price,
    variant_id: i.variant_id,
    product_id: i.product_id,
  })),
  shipping_methods: [...],
})

const context = { ...rawContext, items: rawContext.items ?? [] }
if (!Array.isArray(context.items)) context.items = []

const hasItemsContext = (ctx: Record<string, unknown>): boolean => Array.isArray(ctx.items)

try { await computeActions(codes, context) } catch (e) { if (e.type === MedusaError.Types.INVALID_DATA && /items.*context/.test(e.message)) { /* hydrate items from cart and retry */ } throw e }

When it happens

Trigger: Calling promotionModule.computeActions([promoCode], {}) or with a context missing the items key while any applicable promotion is of type buyget; also passing items: null explicitly.

Common situations: Running computeActions for cart-level discounts without loading the cart first, reusing a shipping-only context (shipping_methods only) with a buy-get code, integration tests with empty context fixtures.

Related errors

• "${contextKey}" should be present as an array in the context
• "shipping_methods" should be present as an array in the cont
• apply_to_quantity is a required field for Promotion type of
• buy_rules_min_quantity is a required field for Promotion typ
• application_method.max_quantity is a required field for Prom

AI-assisted analysis of medusajs/medusa@5e06e544a2 (2026-08-27). Data as JSON: /api/errors/53ef55fe8d6dcfd4. Report an issue: GitHub.