Refactor pagination to user offset, add testing and expand filtering

Author: solomonng2001

firebaseSample/README.md

@@ -0,0 +1,12 @@
+This is the Firebase Golang code. It's meant for the backend people to use this code to jumpstart their own REST API development
+
+## Getting Started
+
+First, run the development server by running `main.exe`
+
+Open [http://localhost:8080/question](http://localhost:8080/question) with your browser to see the result.
+
+Remember to place the `cs3219-g24-firebase-adminsdk-9cm7h-b1675603ab.json` file in the same directory/folder as `main.exe`
+
+DO NOT UPLOAD THE `cs3219-g24-firebase-adminsdk-9cm7h-b1675603ab.json` FILE ONTO GITHUB, OR ELSE THE FIREBASE CODE WILL STOP WORKING!!!
+

services/question-service/handlers/create.go

@@ -1,11 +1,16 @@
 package handlers
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
+	"log"
 	"net/http"
 	"question-service/models"
 	"question-service/utils"
+
+	"cloud.google.com/go/firestore"
+	"google.golang.org/api/iterator"
 )
 
 func (s *Service) CreateQuestion(w http.ResponseWriter, r *http.Request) {
@@ -18,23 +23,71 @@ func (s *Service) CreateQuestion(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// Update database
-	docRef, _, err := s.Client.Collection("questions").Add(ctx, map[string]interface{}{
-		"title":       question.Title,
-		"description": question.Description,
-		"complexity":  question.Complexity,
-		"categories":  question.Categories,
+	// Validation
+	// TODO: Duplicate checking for question name
+
+	// Reference to the document where we store the last ID
+	counterDocRef := s.Client.Collection("counters").Doc("questions")
+
+	// Firestore transaction to implement auto-increment
+	err := s.Client.RunTransaction(ctx, func(ctx context.Context, tx *firestore.Transaction) error {
+		doc, err := tx.Get(counterDocRef)
+		if err != nil {
+			return err
+		}
+
+		// Get the current value of the counter
+		currentCounter := doc.Data()["count"].(int64)
+		newCounter := currentCounter + 1
+
+		// Update the counter in Firestore
+		if err := tx.Set(counterDocRef, map[string]interface{}{
+			"count": newCounter,
+		}); err != nil {
+			return err
+		}
+
+		// Use the newCounter as the ID for the new document
+		docRef, _, err := s.Client.Collection("questions").Add(ctx, map[string]interface{}{
+			"id":          newCounter,
+			"title":       question.Title,
+			"description": question.Description,
+			"complexity":  question.Complexity,
+			"categories":  question.Categories,
+			"createdAt":   firestore.ServerTimestamp,
+		})
+		if err != nil {
+			http.Error(w, "Error adding question", http.StatusInternalServerError)
+			return err
+		}
+
+		// Get data
+		doc, err = docRef.Get(ctx)
+		if err != nil {
+			if err != iterator.Done {
+				http.Error(w, "Question not found", http.StatusNotFound)
+				return err
+			}
+			http.Error(w, "Failed to get question", http.StatusInternalServerError)
+			return err
+		}
+
+		// Map data
+		if err := doc.DataTo(&question); err != nil {
+			http.Error(w, "Failed to map question data", http.StatusInternalServerError)
+			return err
+		}
+		question.DocRefID = doc.Ref.ID
+
+		return nil
 	})
 	if err != nil {
-		http.Error(w, "Error adding question", http.StatusInternalServerError)
+		log.Fatalf("Trasaction failed: %v", err)
 		return
 	}
 
-	// Map data
-	question.Ref = docRef.ID
-
 	w.Header().Set("Content-Type", "application/json")
 	json.NewEncoder(w).Encode(question)
 
-	fmt.Fprintf(w, "Question with ID %s created successfully", question.ID)
+	fmt.Fprintf(w, "Question with ID %s created successfully", question.DocRefID)
 }

services/question-service/handlers/delete.go

@@ -13,10 +13,14 @@ func (s *Service) DeleteQuestion(w http.ResponseWriter, r *http.Request) {
 	ctx := r.Context()
 
 	// Parse request
-	id := chi.URLParam(r, "id")
+	docRefID := chi.URLParam(r, "docRefID")
 
+	// Reference document
+	docRef := s.Client.Collection("questions").Doc(docRefID)
+
+	// Validation
 	// Check if exists
-	_, err := s.Client.Collection("questions").Doc(id).Get(ctx)
+	_, err := docRef.Get(ctx)
 	if err != nil {
 		if status.Code(err) == codes.NotFound {
 			http.Error(w, "Question not found", http.StatusNotFound)
@@ -27,11 +31,11 @@ func (s *Service) DeleteQuestion(w http.ResponseWriter, r *http.Request) {
 	}
 
 	// Update database
-	_, err = s.Client.Collection("questions").Doc(id).Delete(ctx)
+	_, err = docRef.Delete(ctx)
 	if err != nil {
 		http.Error(w, "Error deleting question", http.StatusInternalServerError)
 		return
 	}
 
-	fmt.Fprintf(w, "Question with ID %s deleted successfully", id)
+	fmt.Fprintf(w, "Question with ID %s deleted successfully", docRefID)
 }