Return full item data instead of just ids option

server/rest.go

@@ -539,8 +539,9 @@ func (s *RestServer) CreateWebService() {
 		Param(ws.QueryParameter("write-back-delay", "Timestamp delay of write back feedback (format 0h0m0s)").DataType("string")).
 		Param(ws.QueryParameter("n", "Number of returned items").DataType("integer")).
 		Param(ws.QueryParameter("offset", "Offset of returned items").DataType("integer")).
-		Returns(http.StatusOK, "OK", []string{}).
-		Writes([]string{}))
+		Param(ws.QueryParameter("include-items", "Include full item data in response").DataType("boolean")).
+		Returns(http.StatusOK, "OK", RecommendResponse{}).
+		Writes(RecommendResponse{}))
 	ws.Route(ws.GET("/recommend/{user-id}/{category}").To(s.getRecommend).
 		Deprecate().Doc("Get recommendation for user. Set X-API-Version: 2 to return scores.").
 		Metadata(restfulspec.KeyOpenAPITags, []string{RecommendationAPITag}).
@@ -552,8 +553,9 @@ func (s *RestServer) CreateWebService() {
 		Param(ws.QueryParameter("write-back-delay", "Timestamp delay of write back feedback (format 0h0m0s)").DataType("string")).
 		Param(ws.QueryParameter("n", "Number of returned items").DataType("integer")).
 		Param(ws.QueryParameter("offset", "Offset of returned items").DataType("integer")).
-		Returns(http.StatusOK, "OK", []string{}).
-		Writes([]string{}))
+		Param(ws.QueryParameter("include-items", "Include full item data in response").DataType("boolean")).
+		Returns(http.StatusOK, "OK", RecommendResponse{}).
+		Writes(RecommendResponse{}))
 	ws.Route(ws.POST("/session/recommend").To(s.sessionRecommend).
 		Doc("Get recommendation for session.").
 		Metadata(restfulspec.KeyOpenAPITags, []string{RecommendationAPITag}).
@@ -883,13 +885,33 @@ func (s *RestServer) getRecommend(request *restful.Request, response *restful.Re
 	} else {
 		scores = []cache.Score{}
 	}
-	results := lo.Map(scores, func(item cache.Score, index int) string {
+	itemIds := lo.Map(scores, func(item cache.Score, index int) string {
 		return item.Id
 	})
+	includeItems := request.QueryParameter("include-items") == "true"
+	var items []data.Item
+	if includeItems {
+		// fetch full item data only when requested
+		fetchedItems, err := s.DataClient.BatchGetItems(ctx, itemIds)
+		if err != nil {
+			InternalServerError(response, err)
+			return
+		}
+		// order items to match itemIds order
+		itemMap := make(map[string]data.Item, len(fetchedItems))
+		for _, item := range fetchedItems {
+			itemMap[item.ItemId] = item
+		}
+		for _, id := range itemIds {
+			if item, ok := itemMap[id]; ok {
+				items = append(items, item)
+			}
+		}
+	}
 	// write back
 	if writeBackFeedback != "" {
 		startTime := time.Now()
-		for _, itemId := range results {
+		for _, itemId := range itemIds {
 			// insert to data store
 			feedback := data.Feedback{
 				FeedbackKey: data.FeedbackKey{
@@ -911,7 +933,15 @@ func (s *RestServer) getRecommend(request *restful.Request, response *restful.Re
 		Ok(response, scores)
 		return
 	}
-	Ok(response, results)
+	// Send response: include full item data only when requested
+	if includeItems {
+		Ok(response, RecommendResponse{
+			ItemIds: itemIds,
+			Items:   items,
+		})
+	} else {
+		Ok(response, itemIds)
+	}
 }
 
 func (s *RestServer) sessionRecommend(request *restful.Request, response *restful.Response) {
@@ -1011,6 +1041,13 @@ func (s *RestServer) sessionRecommend(request *restful.Request, response *restfu
 	Ok(response, result)
 }
 
+// RecommendResponse is the response for the recommend endpoint.
+// It includes both item IDs (for backward compatibility) and full item data.
+type RecommendResponse struct {
+	ItemIds []string    `json:"item_ids"`
+	Items   []data.Item `json:"items"`
+}
+
 // Success is the returned data structure for data insert operations.
 type Success struct {
 	RowAffected int

server/rest_test.go

@@ -88,6 +88,25 @@
 	return string(s)
 }
 
+// marshalRecommend builds the expected JSON for the recommend endpoint.
+// It fetches full item data from the test DataClient and orders them to match itemIds.
+func (suite *ServerTestSuite) marshalRecommend(itemIds []string) string {
+	ctx := context.Background()
+	fetched, err := suite.DataClient.BatchGetItems(ctx, itemIds)
+	suite.NoError(err)
+	itemMap := make(map[string]data.Item, len(fetched))
+	for _, item := range fetched {
+		itemMap[item.ItemId] = item
+	}
+	var items []data.Item
+	for _, id := range itemIds {
+		if item, ok := itemMap[id]; ok {
+			items = append(items, item)
+		}
+	}
+	return suite.marshal(RecommendResponse{ItemIds: itemIds, Items: items})
+}
+
 func (suite *ServerTestSuite) TestUsers() {
 	t := suite.T()
 	users := []data.User{
@@ -1083,6 +1102,19 @@
 		Status(http.StatusOK).
 		Body(suite.marshal([]string{"6", "7", "8"})).
 		End()
+	// Test include-items=true returns full item data
+	apitest.New().
+		Handler(suite.handler).
+		Get("/api/recommend/0").
+		Header("X-API-Key", apiKey).
+		QueryParams(map[string]string{
+			"n":             "3",
+			"include-items": "true",
+		}).
+		Expect(suite.T()).
+		Status(http.StatusOK).
+		Body(suite.marshalRecommend([]string{"6", "7", "8"})).
+		End()
 }
 
 func (suite *ServerTestSuite) TestGetRecommendsMultiCategories() {