fix: sort top questions by upvote count

server/routes/questions.js

@@ -5,6 +5,7 @@ const Answer = require('../models/Answer')
 const { authenticateToken } = require('../middleware/auth')
 const { acceptAnswer } = require('../services/answerAcceptance')
 const { voteOnContent, sendVoteResponse } = require('../services/voting')
+const { findQuestionsForList } = require('../services/questionQueries')
 
 const router = express.Router()
 
@@ -23,7 +24,8 @@ router.get('/', async (req, res) => {
       timeRange = 'all'
     } = req.query
 
-    const skip = (page - 1) * limit
+    const parsedLimit = parseInt(limit)
+    const skip = (page - 1) * parsedLimit
     const query = { isDeleted: false }
 
     // Search filter
@@ -83,7 +85,7 @@ router.get('/', async (req, res) => {
         sortOption = { createdAt: 1 }
         break
       case 'votes':
-        sortOption = { 'votes.upvotes': -1 }
+        sortOption = { createdAt: -1 }
         break
       case 'answers':
         sortOption = { answerCount: -1 }
@@ -104,15 +106,16 @@ router.get('/', async (req, res) => {
         break
     }
 
-    const questions = await Question.find(query)
-      .populate('author', 'username reputation avatar')
-      .sort(sortOption)
-      .skip(skip)
-      .limit(parseInt(limit))
-      .lean()
+    const questions = await findQuestionsForList({
+      query,
+      sort,
+      sortOption,
+      skip,
+      limit: parsedLimit
+    })
 
     const total = await Question.countDocuments(query)
-    const totalPages = Math.ceil(total / limit)
+    const totalPages = Math.ceil(total / parsedLimit)
 
     // Add virtual fields
     const questionsWithVirtuals = questions.map(q => ({

server/services/questionQueries.js

@@ -0,0 +1,37 @@
+const Question = require('../models/Question')
+
+const buildTopQuestionsPipeline = (query, skip, limit) => [
+  { $match: query },
+  {
+    $addFields: {
+      upvoteCountForSort: {
+        $size: { $ifNull: ['$votes.upvotes', []] }
+      }
+    }
+  },
+  { $sort: { upvoteCountForSort: -1, createdAt: -1 } },
+  { $skip: skip },
+  { $limit: limit }
+]
+
+const findQuestionsForList = async ({ query, sort, sortOption, skip, limit }) => {
+  if (sort !== 'votes') {
+    return Question.find(query)
+      .populate('author', 'username reputation avatar')
+      .sort(sortOption)
+      .skip(skip)
+      .limit(limit)
+      .lean()
+  }
+
+  const questions = await Question.aggregate(buildTopQuestionsPipeline(query, skip, limit))
+  return Question.populate(questions, {
+    path: 'author',
+    select: 'username reputation avatar'
+  })
+}
+
+module.exports = {
+  buildTopQuestionsPipeline,
+  findQuestionsForList
+}

tests/question-query-service.test.js

@@ -0,0 +1,23 @@
+const { buildTopQuestionsPipeline } = require('../server/services/questionQueries')
+
+describe('question list query helpers', () => {
+  test('top sort computes upvote count instead of sorting by voter object ids', () => {
+    const query = { isDeleted: false }
+
+    const pipeline = buildTopQuestionsPipeline(query, 20, 10)
+
+    expect(pipeline).toEqual([
+      { $match: query },
+      {
+        $addFields: {
+          upvoteCountForSort: {
+            $size: { $ifNull: ['$votes.upvotes', []] }
+          }
+        }
+      },
+      { $sort: { upvoteCountForSort: -1, createdAt: -1 } },
+      { $skip: 20 },
+      { $limit: 10 }
+    ])
+  })
+})