fix: backend history sorting

Author: tituschewxj

apps/history-service/handlers/listquestionhistory.go

@@ -4,8 +4,8 @@ import (
 	"encoding/json"
 	"history-service/models"
 	"net/http"
+	"sort"
 
-	"cloud.google.com/go/firestore"
 	"github.com/go-chi/chi/v5"
 	"google.golang.org/api/iterator"
 )
@@ -23,12 +23,12 @@ func (s *Service) ListUserQuestionHistories(w http.ResponseWriter, r *http.Reque
 	// Query data
 	iterUser := collRef.Where("user", "==", username).
 		Where("questionDocRefId", "==", questionDocRefID).
-		OrderBy("createdAt", firestore.Desc).
 		Documents(ctx)
+	defer iterUser.Stop()
 	iterMatchedUser := collRef.Where("matchedUser", "==", username).
 		Where("questionDocRefId", "==", questionDocRefID).
-		OrderBy("createdAt", firestore.Desc).
 		Documents(ctx)
+	defer iterMatchedUser.Stop()
 
 	// Map data
 	var histories []models.CollaborationHistory
@@ -76,6 +76,9 @@ func (s *Service) ListUserQuestionHistories(w http.ResponseWriter, r *http.Reque
 		histories = append(histories, history)
 	}
 
+	// Sort the histories by created at time
+	sort.Sort(models.HistorySorter(histories))
+
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(http.StatusOK)
 	json.NewEncoder(w).Encode(histories)

apps/history-service/handlers/listuserhistory.go

@@ -4,8 +4,8 @@ import (
 	"encoding/json"
 	"history-service/models"
 	"net/http"
+	"sort"
 
-	"cloud.google.com/go/firestore"
 	"github.com/go-chi/chi/v5"
 	"google.golang.org/api/iterator"
 )
@@ -21,11 +21,11 @@ func (s *Service) ListUserHistories(w http.ResponseWriter, r *http.Request) {
 
 	// Query data
 	iterUser := collRef.Where("user", "==", username).
-		OrderBy("createdAt", firestore.Desc).
 		Documents(ctx)
+	defer iterUser.Stop()
 	iterMatchedUser := collRef.Where("matchedUser", "==", username).
-		OrderBy("createdAt", firestore.Desc).
 		Documents(ctx)
+	defer iterUser.Stop()
 
 	// Map data
 	var histories []models.CollaborationHistory
@@ -73,6 +73,9 @@ func (s *Service) ListUserHistories(w http.ResponseWriter, r *http.Request) {
 		histories = append(histories, history)
 	}
 
+	// Sort the histories by created at time
+	sort.Sort(models.HistorySorter(histories))
+
 	w.Header().Set("Content-Type", "application/json")
 	w.WriteHeader(http.StatusOK)
 	json.NewEncoder(w).Encode(histories)

apps/history-service/models/models.go

@@ -23,3 +23,12 @@ type CollaborationHistory struct {
 	UpdatedAt       time.Time `json:"updatedAt" firestore:"updatedAt"` // updatedAt is unused as history is never updated once created
 	HistoryDocRefID string    `json:"historyDocRefId"`
 }
+
+// Sorting interface for history, which sorts by created at in desc order
+type HistorySorter []CollaborationHistory
+
+func (s HistorySorter) Len() int { return len(s) }
+func (s HistorySorter) Less(i, j int) bool {
+	return s[i].CreatedAt.After(s[j].CreatedAt)
+}
+func (s HistorySorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }