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AD2025
267
middleware/cache.js
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267
middleware/cache.js
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const { getCache, setCache, deleteCache } = require('../config/redis');
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const logger = require('../config/logger');
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/**
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* Cache middleware for GET requests
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* @param {number} ttl - Time to live in seconds (default: 300 = 5 minutes)
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* @param {function} keyGenerator - Function to generate cache key from req
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*/
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const cacheMiddleware = (ttl = 300, keyGenerator = null) => {
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return async (req, res, next) => {
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// Only cache GET requests
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if (req.method !== 'GET') {
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return next();
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}
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try {
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// Generate cache key
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const cacheKey = keyGenerator
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? keyGenerator(req)
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: `cache:${req.originalUrl}`;
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// Try to get from cache
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const cachedData = await getCache(cacheKey);
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if (cachedData) {
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logger.debug(`Cache hit for: ${cacheKey}`);
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return res.status(200).json(cachedData);
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}
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// Cache miss - store original json method
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const originalJson = res.json.bind(res);
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// Override json method to cache response
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res.json = function(data) {
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// Only cache successful responses
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if (res.statusCode === 200) {
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setCache(cacheKey, data, ttl).catch(err => {
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logger.error('Failed to cache response:', err);
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});
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}
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// Call original json method
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return originalJson(data);
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};
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next();
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} catch (error) {
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logger.error('Cache middleware error:', error);
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next(); // Continue even if cache fails
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}
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};
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};
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/**
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* Cache categories (rarely change)
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*/
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const cacheCategories = cacheMiddleware(3600, (req) => {
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// Cache for 1 hour
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return 'cache:categories:list';
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});
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/**
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* Cache single category
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*/
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const cacheSingleCategory = cacheMiddleware(3600, (req) => {
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return `cache:category:${req.params.id}`;
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});
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/**
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* Cache guest settings (rarely change)
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*/
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const cacheGuestSettings = cacheMiddleware(1800, (req) => {
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// Cache for 30 minutes
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return 'cache:guest:settings';
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});
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/**
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* Cache system statistics (update frequently)
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*/
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const cacheStatistics = cacheMiddleware(300, (req) => {
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// Cache for 5 minutes
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return 'cache:admin:statistics';
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});
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/**
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* Cache guest analytics
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*/
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const cacheGuestAnalytics = cacheMiddleware(600, (req) => {
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// Cache for 10 minutes
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return 'cache:admin:guest-analytics';
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});
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/**
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* Cache user dashboard
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*/
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const cacheUserDashboard = cacheMiddleware(300, (req) => {
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// Cache for 5 minutes
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const userId = req.params.userId || req.user?.id;
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return `cache:user:${userId}:dashboard`;
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});
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/**
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* Cache questions list (with filters)
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*/
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const cacheQuestions = cacheMiddleware(600, (req) => {
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// Cache for 10 minutes
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const { categoryId, difficulty, questionType, visibility } = req.query;
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const filters = [categoryId, difficulty, questionType, visibility]
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.filter(Boolean)
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.join(':');
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return `cache:questions:${filters || 'all'}`;
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});
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/**
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* Cache single question
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*/
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const cacheSingleQuestion = cacheMiddleware(1800, (req) => {
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return `cache:question:${req.params.id}`;
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});
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/**
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* Cache user bookmarks
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*/
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const cacheUserBookmarks = cacheMiddleware(300, (req) => {
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const userId = req.params.userId || req.user?.id;
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return `cache:user:${userId}:bookmarks`;
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});
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/**
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* Cache user history
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*/
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const cacheUserHistory = cacheMiddleware(300, (req) => {
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const userId = req.params.userId || req.user?.id;
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const page = req.query.page || 1;
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return `cache:user:${userId}:history:page:${page}`;
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});
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/**
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* Invalidate cache patterns
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*/
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const invalidateCache = {
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/**
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* Invalidate user-related cache
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*/
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user: async (userId) => {
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await deleteCache(`cache:user:${userId}:*`);
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logger.debug(`Invalidated cache for user ${userId}`);
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},
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/**
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* Invalidate category cache
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*/
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category: async (categoryId = null) => {
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if (categoryId) {
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await deleteCache(`cache:category:${categoryId}`);
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}
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await deleteCache('cache:categories:*');
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logger.debug('Invalidated category cache');
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},
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/**
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* Invalidate question cache
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*/
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question: async (questionId = null) => {
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if (questionId) {
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await deleteCache(`cache:question:${questionId}`);
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}
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await deleteCache('cache:questions:*');
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logger.debug('Invalidated question cache');
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},
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/**
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* Invalidate statistics cache
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*/
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statistics: async () => {
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await deleteCache('cache:admin:statistics');
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await deleteCache('cache:admin:guest-analytics');
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logger.debug('Invalidated statistics cache');
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},
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/**
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* Invalidate guest settings cache
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*/
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guestSettings: async () => {
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await deleteCache('cache:guest:settings');
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logger.debug('Invalidated guest settings cache');
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},
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/**
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* Invalidate all quiz-related cache
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*/
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quiz: async (userId = null, guestId = null) => {
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if (userId) {
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await deleteCache(`cache:user:${userId}:*`);
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}
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if (guestId) {
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await deleteCache(`cache:guest:${guestId}:*`);
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}
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await invalidateCache.statistics();
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logger.debug('Invalidated quiz cache');
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}
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};
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/**
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* Middleware to invalidate cache after mutations
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*/
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const invalidateCacheMiddleware = (pattern) => {
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return async (req, res, next) => {
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// Store original json method
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const originalJson = res.json.bind(res);
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// Override json method
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res.json = async function(data) {
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// Only invalidate on successful mutations
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if (res.statusCode >= 200 && res.statusCode < 300) {
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try {
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if (typeof pattern === 'function') {
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await pattern(req);
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} else {
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await deleteCache(pattern);
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}
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} catch (error) {
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logger.error('Cache invalidation error:', error);
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}
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}
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// Call original json method
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return originalJson(data);
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};
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next();
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};
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};
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/**
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* Cache warming - preload frequently accessed data
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*/
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const warmCache = async () => {
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try {
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logger.info('Warming cache...');
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// This would typically fetch and cache common data
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// For now, we'll just log the intent
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// In a real scenario, you'd fetch categories, popular questions, etc.
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logger.info('Cache warming complete');
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} catch (error) {
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logger.error('Cache warming error:', error);
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}
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};
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module.exports = {
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cacheMiddleware,
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cacheCategories,
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cacheSingleCategory,
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cacheGuestSettings,
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cacheStatistics,
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cacheGuestAnalytics,
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cacheUserDashboard,
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cacheQuestions,
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cacheSingleQuestion,
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cacheUserBookmarks,
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cacheUserHistory,
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invalidateCache,
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invalidateCacheMiddleware,
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warmCache
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};
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