Nodejs Data Caching with Redis Part 1: Caching in Action

You have to install Redis, Another Redis Desktop Manager and NPM Redis for this example.

Install Redis on Linux

https://hackernoon.com/using-redis-with-node-js-8d87a48c5dd7

Install Redis on Window

https://divyanshushekhar.com/how-to-install-redis-on-windows-10/

https://redislabs.com/blog/redis-on-windows-8-1-and-previous-versions/

Install free version Another Redis Desktop Manager to view the cache data. 

https://github.com/qishibo/AnotherRedisDesktopManager

Install NPM Redis

npm install redis

This is how you connect redis in NodeJS:

const redis = require('redis')

const redisURL = 'redis://127.0.0.1:6379'

const client = redis.createClient(redisURL)

For basic value, you can use set and get method. The first parameter is the search key and second parameter value stored.

// Store 'hi' as search key, and value is 'there'.

client.set('hi','there');

// Output: there

client.get('hi', ( err, val) => { console.log(val) } )

Redis support hset where you can have 2 search keys. Generally, I think it is practical to use hset for mongodb where the search keys are collection name and search query.

You may refer example on CRUD in StudentController:

https://github.com/htsiah/node-redis-mongodb

Create - http://localhost/api/student

- When there is new document, delete collection in the cache.

redisClient.del(StudentModel.collection.collectionName)

Read - http://localhost/api/student/6028c376ddf84b2bd0a6b6b3

- If there is cache data, return cache data.

      const cacheStudent = await redisClient.hget(

        StudentModel.collection.collectionName, 

        JSON.stringify(query.getQuery())

      )

      if (cacheStudent) {

        // Remember convert to javascript object

        console.log('Get from cache.')

        return res.json(JSON.parse(cacheStudent)); 

      }  

- If not, find the data in mongodb, store the data to redis and return the data.

      const student = await query.exec();

      redisClient.hset(

        StudentModel.collection.collectionName, 

        JSON.stringify(query.getQuery()), 

        JSON.stringify(student.toObject({ getters: false }))

      )

Update - http://localhost/api/student/6028c376ddf84b2bd0a6b6b3

- Same as create, delete the collection.

Delete - http://localhost/api/student/6028c376ddf84b2bd0a6b6b3

- Same as create, delete the collection.

The above is an example using collection as key. The different requirement may use different key.