Using Redis with Node.js

When trying to optimise our applications, one of the first things we look to is caching. Caching involves storing data in a high performance store (many times temporarily) so such data can be retrieved faster at a later time. Redis is an efficient key-value data store that has become very popular for caching. One of the things that makes Redis a good choice is the number of data structures it supports — such as strings, hashes, lists, sets, and so on. This gives us some flexibility!

The first step is to enter the following command to create the initial structure of your new project:

npm init

Then, we have to install Express and the MongoDB driver and save them as dependencies:

npm install express --save
npm install mongodb --save

Now, it’s time to create the main file called index.js. It’s the file where we’ll do most of our work. Start off by creating a simple app, connecting it to MongoDB and listening on port 7000:

//Define all dependencies needed
const express = require('express');
var MongoClient = require('mongodb').MongoClient;
var app = express();

var database="";
MongoClient.connect("mongodb://localhost:27017/demo", function(err, db) {
  if(!err) {
    console.log("We are connected");
    database=db;
   console.log(database);
  }
  else {
    console.log(err);
  }
});

app.listen(7000, function() {
  console.log('Your node is running on port 7000 !!!')
});

Once you have done with Express and MongoDB you are good to go. Let’s create add below two lines index.js, and see how to connect with Redis from Node.js.

const redis = require('redis');
const client = redis.createClient();

By default, redis.createClient() will use 127.0.0.1 and 6379 as the hostname and port respectively. If you have a different host/port you can supply them as following:

const client = redis.createClient(port, host);

Storing Key-Value Pairs

Now that you know how to connect with Redis from Node.js, let’s see how to store key-value pairs in Redis storage.

const getProjects = (req, res) => {
  database.collection('projects').find({"project_id":req.body.id}).toArray(function(err, col) {
    if(err) throw err
    client.setex(req.body, 60, JSON.stringify(col));
    res.json(col);
  
  });
}

The above snippets store a simple JSON fetched from database against the key framework and here req.body is the Key.

To retrieve the value of the key do the following:

const getCache = (req, res) => {
  
  //Check the cache data from the server redis
  client.get(req.body, (err, result) => {
    if (result) {
      res.send(result);
    } else {
      getProjects(req, res);
    }
  });
}

app.get('/projects',getCache);

client.get() lets you retrieve a key stored in Redis. The value of the key can be accessed via the callback argument reply. If the key doesn’t exist, the value of result will be empty.

Conclusion

I have covered the basic and most commonly used operations in node_redis. You can use this module to leverage the full power of Redis and create really sophisticated Node.js apps. You can build many interesting things with this library such as a strong caching layer, a powerful Pub/Sub messaging system and more. To know more about the library check out their documentation.