Add duplicate check for update question

Author: jolynloh

backend/question-service/src/controllers/questionController.ts

@@ -1,5 +1,7 @@
 import { Request, Response } from "express";
 import Question from "../models/Question.ts";
+import { checkIsExistingQuestion } from "../utils/utils.ts";
+import { DUPLICATE_QUESTION_RESPONSE_MESSAGE } from "../utils/constants.ts";
 
 export const createQuestion = async (
   req: Request,
@@ -8,14 +10,10 @@ export const createQuestion = async (
   try {
     const { title, description, complexity, category } = req.body;
 
-    const existingQuestion = await Question.findOne({
-      title: new RegExp(`^${title}$`, "i"),
-    });
-
+    const existingQuestion = await checkIsExistingQuestion(title);
     if (existingQuestion) {
       res.status(400).json({
-        message:
-          "Duplicate question: A question with the same title already exists.",
+        message: DUPLICATE_QUESTION_RESPONSE_MESSAGE,
       });
       return;
     }
@@ -44,14 +42,26 @@ export const updateQuestion = async (
 ): Promise<void> => {
   try {
     const { id } = req.params;
-    const updatedQuestion = await Question.findByIdAndUpdate(id, req.body, {
-      new: true,
-    });
-    if (!updatedQuestion) {
+    const { title } = req.body;
+
+    const currentQuestion = await Question.findById(id);
+    if (!currentQuestion) {
       res.status(404).json({ message: "Question not found" });
       return;
     }
 
+    const existingQuestion = await checkIsExistingQuestion(title, id);
+    if (existingQuestion) {
+      res.status(400).json({
+        message: DUPLICATE_QUESTION_RESPONSE_MESSAGE,
+      });
+      return;
+    }
+
+    const updatedQuestion = await Question.findByIdAndUpdate(id, req.body, {
+      new: true,
+    });
+
     res.status(200).json({
       message: "Question updated successfully",
       question: updatedQuestion,

backend/question-service/src/utils/constants.ts

@@ -0,0 +1,2 @@
+export const DUPLICATE_QUESTION_RESPONSE_MESSAGE =
+  "Duplicate question: A question with the same title already exists.";

backend/question-service/src/utils/utils.ts

@@ -0,0 +1,17 @@
+import mongoose from "mongoose";
+
+import Question from "../models/Question";
+
+export const checkIsExistingQuestion = async (
+  title: string,
+  idToExcludeFromCheck = "",
+) => {
+  const objectIdToExclude = idToExcludeFromCheck
+    ? new mongoose.Types.ObjectId(idToExcludeFromCheck)
+    : null;
+
+  return await Question.findOne({
+    title: new RegExp(`^${title}$`, "i"),
+    _id: { $ne: objectIdToExclude }, // Exclude current question's ID if provided
+  });
+};