fix: ensures no duplicate tax lines when completing cart (#1262)

* fix: ensures that no duplicate tax lines are created when completing cart

packages/medusa/src/migrations/1648641130007-tax_line_constraints.ts

@@ -0,0 +1,23 @@
+import { MigrationInterface, QueryRunner } from "typeorm"
+
+export class taxLineConstraints1648641130007 implements MigrationInterface {
+  name = "taxLineConstraints1648641130007"
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "line_item_tax_line" ADD CONSTRAINT "UQ_3c2af51043ed7243e7d9775a2ad" UNIQUE ("item_id", "code")`
+    )
+    await queryRunner.query(
+      `ALTER TABLE "shipping_method_tax_line" ADD CONSTRAINT "UQ_cd147fca71e50bc954139fa3104" UNIQUE ("shipping_method_id", "code")`
+    )
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "shipping_method_tax_line" DROP CONSTRAINT "UQ_cd147fca71e50bc954139fa3104"`
+    )
+    await queryRunner.query(
+      `ALTER TABLE "line_item_tax_line" DROP CONSTRAINT "UQ_3c2af51043ed7243e7d9775a2ad"`
+    )
+  }
+}

packages/medusa/src/models/line-item-tax-line.ts

@@ -1,10 +1,11 @@
 import {
-  Entity,
   BeforeInsert,
-  Index,
   Column,
-  ManyToOne,
+  Entity,
+  Index,
   JoinColumn,
+  ManyToOne,
+  Unique,
 } from "typeorm"
 import { ulid } from "ulid"
 
@@ -12,6 +13,7 @@ import { TaxLine } from "./tax-line"
 import { LineItem } from "./line-item"
 
 @Entity()
+@Unique(["item_id", "code"])
 export class LineItemTaxLine extends TaxLine {
   @Index()
   @Column()

packages/medusa/src/models/shipping-method-tax-line.ts

@@ -1,10 +1,11 @@
 import {
-  Entity,
   BeforeInsert,
-  Index,
   Column,
-  ManyToOne,
+  Entity,
+  Index,
   JoinColumn,
+  ManyToOne,
+  Unique,
 } from "typeorm"
 import { ulid } from "ulid"
 
@@ -12,6 +13,7 @@ import { TaxLine } from "./tax-line"
 import { ShippingMethod } from "./shipping-method"
 
 @Entity()
+@Unique(["shipping_method_id", "code"])
 export class ShippingMethodTaxLine extends TaxLine {
   @Index()
   @Column()

packages/medusa/src/repositories/line-item-tax-line.ts

@@ -2,4 +2,36 @@ import { EntityRepository, Repository } from "typeorm"
 import { LineItemTaxLine } from "../models/line-item-tax-line"
 
 @EntityRepository(LineItemTaxLine)
-export class LineItemTaxLineRepository extends Repository<LineItemTaxLine> {}
+export class LineItemTaxLineRepository extends Repository<LineItemTaxLine> {
+  async upsertLines(lines: LineItemTaxLine[]): Promise<LineItemTaxLine[]> {
+    const insertResult = await this.createQueryBuilder()
+      .insert()
+      .values(lines)
+      .orUpdate({
+        conflict_target: ["item_id", "code"],
+        overwrite: ["rate", "name", "updated_at"],
+      })
+      .execute()
+
+    return insertResult.identifiers as LineItemTaxLine[]
+  }
+
+  async deleteForCart(cartId: string): Promise<void> {
+    const qb = this.createQueryBuilder("line")
+      .select(["line.id"])
+      .innerJoin("line_item", "i", "i.id = line.item_id")
+      .innerJoin(
+        "cart",
+        "c",
+        "i.cart_id = :cartId AND c.completed_at is NULL",
+        { cartId }
+      )
+
+    const toDelete = await qb.getMany()
+
+    await this.createQueryBuilder()
+      .delete()
+      .whereInIds(toDelete.map((d) => d.id))
+      .execute()
+  }
+}

packages/medusa/src/repositories/shipping-method-tax-line.ts

@@ -2,4 +2,38 @@ import { EntityRepository, Repository } from "typeorm"
 import { ShippingMethodTaxLine } from "../models/shipping-method-tax-line"
 
 @EntityRepository(ShippingMethodTaxLine)
-export class ShippingMethodTaxLineRepository extends Repository<ShippingMethodTaxLine> {}
+export class ShippingMethodTaxLineRepository extends Repository<ShippingMethodTaxLine> {
+  async upsertLines(
+    lines: ShippingMethodTaxLine[]
+  ): Promise<ShippingMethodTaxLine[]> {
+    const insertResult = await this.createQueryBuilder()
+      .insert()
+      .values(lines)
+      .orUpdate({
+        conflict_target: ["shipping_method_id", "code"],
+        overwrite: ["rate", "name", "updated_at"],
+      })
+      .execute()
+
+    return insertResult.identifiers as ShippingMethodTaxLine[]
+  }
+
+  async deleteForCart(cartId: string): Promise<void> {
+    const qb = this.createQueryBuilder("line")
+      .select(["line.id"])
+      .innerJoin("shipping_method", "sm", "sm.id = line.shipping_method_id")
+      .innerJoin(
+        "cart",
+        "c",
+        "sm.cart_id = :cartId AND c.completed_at is NULL",
+        { cartId }
+      )
+
+    const toDelete = await qb.getMany()
+
+    await this.createQueryBuilder()
+      .delete()
+      .whereInIds(toDelete.map((d) => d.id))
+      .execute()
+  }
+}

packages/medusa/src/services/cart.ts

@@ -1213,6 +1213,13 @@ class CartService extends BaseService {
         return cartRepository.save(cart)
       }
 
+      if (!cart.payment_session) {
+        throw new MedusaError(
+          MedusaError.Types.NOT_ALLOWED,
+          "You cannot complete a cart without a payment session."
+        )
+      }
+
       const session = await this.paymentProviderService_
         .withTransaction(manager)
         .authorizePayment(cart.payment_session, context)
@@ -1874,9 +1881,8 @@ class CartService extends BaseService {
       })
       const calculationContext = this.totalsService_.getCalculationContext(cart)
 
-      await this.taxProviderService_
-        .withTransaction(manager)
-        .createTaxLines(cart, calculationContext)
+      const txTaxProvider = this.taxProviderService_.withTransaction(manager)
+      await txTaxProvider.createTaxLines(cart, calculationContext)
 
       return cart
     })

packages/medusa/src/services/tax-provider.ts

@@ -1,7 +1,7 @@
 import { MedusaError } from "medusa-core-utils"
 import { AwilixContainer } from "awilix"
 import { BaseService } from "medusa-interfaces"
-import { EntityManager } from "typeorm"
+import { EntityManager, UpdateResult } from "typeorm"
 import Redis from "ioredis"
 
 import { LineItemTaxLineRepository } from "../repositories/line-item-tax-line"
@@ -15,6 +15,7 @@ import { ShippingMethod } from "../models/shipping-method"
 import { Region } from "../models/region"
 import { Cart } from "../models/cart"
 import { isCart } from "../types/cart"
+import { PostgresError } from "../utils/exception-formatter"
 import {
   ITaxService,
   ItemTaxCalculationLine,
@@ -94,6 +95,18 @@ class TaxProviderService extends BaseService {
     return provider
   }
 
+  async clearTaxLines(cartId: string): Promise<void> {
+    const taxLineRepo = this.manager_.getCustomRepository(this.taxLineRepo_)
+    const shippingTaxRepo = this.manager_.getCustomRepository(
+      this.smTaxLineRepo_
+    )
+
+    await Promise.all([
+      taxLineRepo.deleteForCart(cartId),
+      shippingTaxRepo.deleteForCart(cartId),
+    ])
+  }
+
   /**
    * Persists the tax lines relevant for an order to the database.
    * @param cartOrLineItems - the cart or line items to create tax lines for
@@ -114,7 +127,33 @@ class TaxProviderService extends BaseService {
       taxLines = await this.getTaxLines(cartOrLineItems, calculationContext)
     }
 
-    return this.manager_.save(taxLines)
+    const itemTaxLineRepo = this.manager_.getCustomRepository(this.taxLineRepo_)
+    const shippingTaxLineRepo = this.manager_.getCustomRepository(
+      this.smTaxLineRepo_
+    )
+
+    const { shipping, lineItems } = taxLines.reduce<{
+      shipping: ShippingMethodTaxLine[]
+      lineItems: LineItemTaxLine[]
+    }>(
+      (acc, tl) => {
+        if ("item_id" in tl) {
+          acc.lineItems.push(tl)
+        } else {
+          acc.shipping.push(tl)
+        }
+
+        return acc
+      },
+      { shipping: [], lineItems: [] }
+    )
+
+    return (
+      await Promise.all([
+        itemTaxLineRepo.upsertLines(lineItems),
+        shippingTaxLineRepo.upsertLines(shipping),
+      ])
+    ).flat()
   }
 
   /**