fix(medusa): quantity prices for line item updates (#5137)

* initial code push

* update metadata and only merge if the existing line item allows merging

* update should_merge check

* undo changes to taxrate service

* update results with unit pricing corresponding to the db values after update

* add should_merge property to line_item creation

* add should_merge property to line_item creation

* fix unit tests

* undo adding "should_merge" to create-line-item

* undo change to "addOrUpdateLineItem"

* :wqh_merge from generate method

* undo changes to unit tests

* revert to adding pricing in updateLineItem method

* update cart service test

* Create funny-radios-juggle.md

---------

Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

packages/medusa/src/api/routes/admin/draft-orders/create-line-item.ts

@@ -1,4 +1,10 @@
-import { IsInt, IsObject, IsOptional, IsString } from "class-validator"
+import {
+  IsBoolean,
+  IsInt,
+  IsObject,
+  IsOptional,
+  IsString,
+} from "class-validator"
 import {
   defaultAdminDraftOrdersCartFields,
   defaultAdminDraftOrdersCartRelations,
@@ -114,7 +120,10 @@ export default async (req, res) => {
           validated.variant_id,
           draftOrder.cart.region_id,
           validated.quantity,
-          { metadata: validated.metadata, unit_price: validated.unit_price }
+          {
+            metadata: validated.metadata,
+            unit_price: validated.unit_price,
+          }
         )
 
       await cartService

packages/medusa/src/api/routes/store/carts/update-line-item.ts

@@ -4,6 +4,7 @@ import { EntityManager } from "typeorm"
 import { defaultStoreCartFields, defaultStoreCartRelations } from "."
 import { CartService } from "../../../../services"
 import { cleanResponseData } from "../../../../utils/clean-response-data"
+import { handleAddOrUpdateLineItem } from "./create-line-item/utils/handler-steps"
 
 /**
  * @oas [post] /store/carts/{id}/line-items/{line_id}

packages/medusa/src/services/__mocks__/cart.js

@@ -77,6 +77,7 @@ export const carts = {
         title: "merge line",
         description: "This is a new line",
         thumbnail: "test-img-yeah.com/thumb",
+        variant_id: IdMap.getId("eur-10-us-12"),
         unit_price: 10,
         variant: {
           id: IdMap.getId("eur-10-us-12"),

packages/medusa/src/services/__mocks__/line-item.js

@@ -58,7 +58,7 @@ export const LineItemServiceMock = {
         variant_id: variantId,
         unit_price: 100,
         quantity,
-        metadata,
+        ...metadata,
       })
     }),
   delete: jest.fn().mockImplementation(() => Promise.resolve()),

packages/medusa/src/services/__tests__/cart.js

@@ -21,7 +21,7 @@ import { ShippingOptionServiceMock } from "../__mocks__/shipping-option"
 import { ShippingProfileServiceMock } from "../__mocks__/shipping-profile"
 import { taxProviderServiceMock } from "../__mocks__/tax-provider"
 import CartService from "../cart"
-import { NewTotalsService, TaxProviderService } from "../index"
+import { NewTotalsService, PricingService, TaxProviderService } from "../index"
 import SystemTaxService from "../system-tax"
 
 const eventBusService = {
@@ -2657,6 +2657,7 @@ describe("CartService", () => {
       .register("taxProviderService", asClass(TaxProviderService))
       .register("newTotalsService", asClass(NewTotalsService))
       .register("cartService", asClass(CartService))
+      .register("pricingService", asClass(PricingService))
 
     const cartService = container.resolve("cartService")
 

packages/medusa/src/services/cart.ts

@@ -12,6 +12,7 @@ import {
   LineItemService,
   NewTotalsService,
   PaymentProviderService,
+  PricingService,
   ProductService,
   ProductVariantInventoryService,
   ProductVariantService,
@@ -62,6 +63,7 @@ import {
 import { PaymentSessionInput } from "../types/payment"
 import { buildQuery, isString, setMetadata } from "../utils"
 import { validateEmail } from "../utils/is-email"
+import { IsNumber } from "class-validator"
 
 type InjectedDependencies = {
   manager: EntityManager
@@ -91,6 +93,7 @@ type InjectedDependencies = {
   lineItemAdjustmentService: LineItemAdjustmentService
   priceSelectionStrategy: IPriceSelectionStrategy
   productVariantInventoryService: ProductVariantInventoryService
+  pricingService: PricingService
 }
 
 type TotalsConfig = {
@@ -134,6 +137,7 @@ class CartService extends TransactionBaseService {
   protected readonly featureFlagRouter_: FlagRouter
   // eslint-disable-next-line max-len
   protected readonly productVariantInventoryService_: ProductVariantInventoryService
+  protected readonly pricingService_: PricingService
 
   constructor({
     cartRepository,
@@ -162,6 +166,7 @@ class CartService extends TransactionBaseService {
     featureFlagRouter,
     storeService,
     productVariantInventoryService,
+    pricingService,
   }: InjectedDependencies) {
     // eslint-disable-next-line prefer-rest-params
     super(arguments[0])
@@ -192,6 +197,7 @@ class CartService extends TransactionBaseService {
     this.featureFlagRouter_ = featureFlagRouter
     this.storeService_ = storeService
     this.productVariantInventoryService_ = productVariantInventoryService
+    this.pricingService_ = pricingService
   }
 
   /**
@@ -975,7 +981,7 @@ class CartService extends TransactionBaseService {
   ): Promise<Cart> {
     return await this.atomicPhase_(
       async (transactionManager: EntityManager) => {
-        const select: (keyof Cart)[] = ["id"]
+        const select: (keyof Cart)[] = ["id", "region_id", "customer_id"]
         if (
           this.featureFlagRouter_.isFeatureEnabled(SalesChannelFeatureFlag.key)
         ) {
@@ -1014,6 +1020,25 @@ class CartService extends TransactionBaseService {
                 "Inventory doesn't cover the desired quantity"
               )
             }
+
+            const variantsPricing = await this.pricingService_
+              .withTransaction(transactionManager)
+              .getProductVariantsPricing(
+                [
+                  {
+                    variantId: lineItem.variant_id,
+                    quantity: lineItemUpdate.quantity,
+                  },
+                ],
+                {
+                  region_id: cart.region_id,
+                  customer_id: cart.customer_id,
+                  include_discount_prices: true,
+                }
+              )
+
+            const { calculated_price } = variantsPricing[lineItem.variant_id]
+            lineItemUpdate.unit_price = calculated_price ?? undefined
           }
         }
 

packages/medusa/src/strategies/tax-calculation.ts

@@ -2,10 +2,10 @@ import { FlagRouter } from "@medusajs/utils"
 import { ITaxCalculationStrategy, TaxCalculationContext } from "../interfaces"
 import TaxInclusivePricingFeatureFlag from "../loaders/feature-flags/tax-inclusive-pricing"
 import {
-    LineItem,
-    LineItemTaxLine,
-    ShippingMethod,
-    ShippingMethodTaxLine,
+  LineItem,
+  LineItemTaxLine,
+  ShippingMethod,
+  ShippingMethodTaxLine,
 } from "../models"
 import { calculatePriceTaxAmount } from "../utils"
 
@@ -28,13 +28,18 @@ class TaxCalculationStrategy implements ITaxCalculationStrategy {
       (tl) => "shipping_method_id" in tl
     ) as ShippingMethodTaxLine[]
 
-    return Math.round(
-      this.calculateLineItemsTax(items, lineItemsTaxLines, calculationContext) +
-        this.calculateShippingMethodsTax(
-          calculationContext.shipping_methods,
-          shippingMethodsTaxLines
-        )
+    const lineItemsTax = this.calculateLineItemsTax(
+      items,
+      lineItemsTaxLines,
+      calculationContext
     )
+
+    const shippingMethodsTax = this.calculateShippingMethodsTax(
+      calculationContext.shipping_methods,
+      shippingMethodsTaxLines
+    )
+
+    return Math.round(lineItemsTax + shippingMethodsTax)
   }
 
   private calculateLineItemsTax(