Using Redis To Cache Data In NodeJS And ExpressJS Server.

redis image

What is Cache?

• The Cache is Local Storage that is used to store frequently used data .
• Caching is the process of storing copies of files in a cache, or temporary storage location so that they can be accessed more quickly.

What is Redis?

• Redis Stands for Remote Dictionary Server.
• Redis is an open-source, in-memory key-value data store for use as a database, cache, message broker, and queue.

Install Redis Server:

Step 1: Download the latest Redis zip file from the official git hub location. For me it is Redis-2.4.5-win32-win64.zip.

Step 2: Extract the redis-2.4.5-win32-win64.zip file in your preferred location.

Step 3: It will come with two different folders, one is for 32bit, and another one is for 64bit based on your operating system.

Step 4: Goto 64bit there you can find the below files.

Step 4: Double click on the redis-server.exe file, there you can see the Redis-server startup and wait for connecting to clients like below.

Step 5: Now open the Redis-cli.exe file to Redis command-line interface.

As this acts as a Redis client, as soon as we open this cli, we can see the client-connected message in Redis server like below.

• Once Redis is installed then there are 2 ways to use Redis:-

1. Installing Redis-CLI.
2. Use Redis in the server application.

Step-1:- create Basic Express Server and installing packages.

• Once the Express server is created, now install the npm package named “ Axios ” to make a request to any third-party APIs. and import it.

npm install axios --save

• now create a route to handle the GET method on “ /starwar ” path.
• user parameters passed while accessing path to fetch data from a third party using Axios package.

Step:-2 Caching data using Redis.

• install Redis npm package.

npm i redis --save

• we have to first import redis npm package.
• Redis package gives us createClient() method which will accept Redis-server port no which is 6379 by default.
• In case any error arrives we can use client.on(“error”,()=>{}). middleware to log the error message.
• now while handling “/starwars ” route we have to cache the data received into Redis using client.setex() method.

Step:-3 Adding Middleware to check if data is present in Cache or not.

• Now we have to create middleware named checkCache ,which will have access to req,res and next.
• In side Middleware we can use client.get() method to check if required data is in cache or not.
• client.get() method will accept string as first parameter and call back function as second parameter.
• we can pass name of key which we need to search in Cache as first parameter.
• at last, we have to add this middleware in the route handler.