feat: add extend param for customer groups

integration-tests/api/__tests__/admin/customer-groups.js

@@ -120,6 +120,31 @@ describe("/admin/customer-groups", () => {
           name: "vip-customers",
         })
       )
+      expect(response.data.customerGroup).not.toHaveProperty("customers:")
+    })
+
+    it("gets customer group with `customers` prop", async () => {
+      const api = useApi()
+
+      const id = "customer-group-1"
+
+      const response = await api.get(
+        `/admin/customer-groups/${id}?expand=customers`,
+        {
+          headers: {
+            Authorization: "Bearer test_token",
+          },
+        }
+      )
+
+      expect(response.status).toEqual(200)
+      expect(response.data.customerGroup).toEqual(
+        expect.objectContaining({
+          id: "customer-group-1",
+          name: "vip-customers",
+        })
+      )
+      expect(response.data.customerGroup.customers).toEqual([])
     })
 
     it("throws error when a customer group doesn't exist", async () => {

packages/medusa/src/api/routes/admin/customer-groups/get-customer-group.ts

@@ -1,4 +1,7 @@
 import { CustomerGroupService } from "../../../../services"
+import { FindParams } from "../../../../types/common"
+import { validator } from "../../../../utils/validator"
+import { defaultAdminCustomerGroupsRelations } from "."
 
 /**
  * @oas [get] /customer-group/{id}
@@ -22,11 +25,25 @@ import { CustomerGroupService } from "../../../../services"
  */
 export default async (req, res) => {
   const { id } = req.params
+
+  const validated = await validator(FindParams, req.query)
+
   const customerGroupService: CustomerGroupService = req.scope.resolve(
     "customerGroupService"
   )
 
-  const customerGroup = await customerGroupService.retrieve(id)
+  let expandFields: string[] = []
+  if (validated.expand) {
+    expandFields = validated.expand.split(",")
+  }
+
+  const findConfig = {
+    relations: expandFields.length
+      ? expandFields
+      : defaultAdminCustomerGroupsRelations,
+  }
+
+  const customerGroup = await customerGroupService.retrieve(id, findConfig)
 
   res.json({ customerGroup })
 }

packages/medusa/src/api/routes/admin/customer-groups/index.ts

@@ -23,4 +23,6 @@ export type AdminCustomerGroupsListRes = PaginatedResponse & {
   customer_groups: CustomerGroup[]
 }
 
+export const defaultAdminCustomerGroupsRelations = []
+
 export * from "./create-customer-group"