Implement Redis Caching Layer (Fixes #168)

server/package.json

@@ -22,6 +22,7 @@
     "mongoose": "^8.3.1",
     "pdfkit": "^0.19.1",
     "qrcode": "^1.5.4",
+    "redis": "^6.1.0",
     "speakeasy": "^2.0.0",
     "winston": "^3.19.0"
   },

server/routes/medicines.js

@@ -10,12 +10,22 @@ const medicinesLimiter = rateLimit({
 router.use(medicinesLimiter);
 const Medicine = require('../models/Medicine');
 const authMiddleware = require('../middleware/authMiddleware');
+const redisClient = require('../utils/redisClient');
 
 // @route   GET /api/medicines
 // @desc    Get all medicines for the logged-in user
 // @access  Private
 router.get('/', authMiddleware, async (req, res) => {
   try {
+    const cacheKey = `meds_${req.user._id}`;
+
+    if (redisClient.isConnected()) {
+      const cachedData = await redisClient.getClient().get(cacheKey);
+      if (cachedData) {
+        return res.json(JSON.parse(cachedData));
+      }
+    }
+
     const medicines = await Medicine.find({ user: { $eq: req.user._id } }).sort({ createdAt: 1 });
 
     // Format medicines to match the frontend expectations: { id, name, time, date }
@@ -26,6 +36,10 @@ router.get('/', authMiddleware, async (req, res) => {
       date: med.date,
     }));
 
+    if (redisClient.isConnected()) {
+      await redisClient.getClient().setEx(cacheKey, 300, JSON.stringify(formatted)); // Cache for 5 mins
+    }
+
     res.json(formatted);
   } catch (err) {
     console.error('Fetch medicines error:', err.message);
@@ -61,6 +75,10 @@ router.post('/', authMiddleware, async (req, res) => {
       time: newMedicine.time,
       date: newMedicine.date,
     });
+
+    if (redisClient.isConnected()) {
+      await redisClient.getClient().del(`meds_${req.user._id}`);
+    }
   } catch (err) {
     console.error('Add medicine error:', err.message);
     res.status(500).json({ message: 'Server error adding medicine reminder' });
@@ -80,6 +98,11 @@ router.delete('/:id', authMiddleware, async (req, res) => {
     }
 
     await medicine.deleteOne();
+
+    if (redisClient.isConnected()) {
+      await redisClient.getClient().del(`meds_${req.user._id}`);
+    }
+
     res.json({ message: 'Medicine reminder deleted successfully', id: req.params.id });
   } catch (err) {
     console.error('Delete medicine error:', err.message);

server/utils/redisClient.js

@@ -0,0 +1,31 @@
+const redis = require('redis');
+
+let redisClient;
+let isRedisConnected = false;
+
+(async () => {
+  redisClient = redis.createClient({
+    url: process.env.REDIS_URL || 'redis://127.0.0.1:6379'
+  });
+
+  redisClient.on('error', (error) => {
+    console.error(`Redis Error: ${error}`);
+    isRedisConnected = false;
+  });
+
+  redisClient.on('connect', () => {
+    console.log('Redis connected');
+    isRedisConnected = true;
+  });
+
+  try {
+    await redisClient.connect();
+  } catch (err) {
+    console.warn('Redis failed to connect initially. Falling back to DB queries.');
+  }
+})();
+
+module.exports = {
+  getClient: () => redisClient,
+  isConnected: () => isRedisConnected
+};