fix(medusa): fetching a product without a category with categories filed passed (#13020)

**What**
- adding `categories` to `fields` param would return 404 for an existing product if the product was not associated with a category

---

CLOSES CMRC-1046

packages/medusa/src/api/store/products/[id]/route.ts

@@ -2,6 +2,7 @@ import { isPresent, MedusaError } from "@medusajs/framework/utils"
 import { MedusaResponse } from "@medusajs/framework/http"
 import { wrapVariantsWithInventoryQuantityForSalesChannel } from "../../../utils/middlewares"
 import {
+  filterOutInternalProductCategories,
   refetchProduct,
   RequestWithContext,
   wrapProductsWithTaxPrices,
@@ -33,6 +34,14 @@ export const GET = async (
     }
   }
 
+  const includesCategoriesField = req.queryConfig.fields.some((field) =>
+    field.startsWith("categories")
+  )
+
+  if (!req.queryConfig.fields.includes("categories.is_internal")) {
+    req.queryConfig.fields.push("categories.is_internal")
+  }
+
   const product = await refetchProduct(
     filters,
     req.scope,
@@ -53,6 +62,10 @@ export const GET = async (
     )
   }
 
+  if (includesCategoriesField) {
+    filterOutInternalProductCategories([product])
+  }
+
   await wrapProductsWithTaxPrices(req, [product])
   res.json({ product })
 }

packages/medusa/src/api/store/products/helpers.ts

@@ -28,6 +28,22 @@ export const refetchProduct = async (
   return await refetchEntity("product", idOrFilter, scope, fields)
 }
 
+export const filterOutInternalProductCategories = (
+  products: HttpTypes.StoreProduct[]
+) => {
+  return products.forEach((product: HttpTypes.StoreProduct) => {
+    if (!product.categories) {
+      return
+    }
+
+    product.categories = product.categories.filter(
+      (category) =>
+        !(category as HttpTypes.StoreProductCategory & { is_internal: boolean })
+          .is_internal
+    )
+  })
+}
+
 export const wrapProductsWithTaxPrices = async <T>(
   req: RequestWithContext<T>,
   products: HttpTypes.StoreProduct[]

packages/medusa/src/api/store/products/middlewares.ts

@@ -93,13 +93,6 @@ export const storeProductRoutesMiddlewares: MiddlewareRoute[] = [
       }),
       applyDefaultFilters({
         status: ProductStatus.PUBLISHED,
-        categories: (_filters, fields: string[]) => {
-          if (!fields.some((field) => field.startsWith("categories"))) {
-            return
-          }
-
-          return { is_internal: false, is_active: true }
-        },
       }),
       normalizeDataForContext(),
       setPricingContext(),