How to Use Redis with Node.js

One of the most popular libraries for working with Redis server in a Node.js application is node-redis, which can be found at https://github.com/NodeRedis/node-redis.

To install the library in your project, run the following command:

1	npm install redis

Tip: If your project is brand new and does not have a package.json file, make sure to run npm init -y first.

Connecting to the Redis Instance

Once the library is installed, require it in your project using:

1	const redis = require('redis')

1	import redis from 'redis'

After you have the redis object, create a new client using:

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const client = redis.createClient({
 url: 'redis://YOUR REDIS INSTANCE URL'
})

and connect to the Redis server using (inside an async function):

1	await client.connect()

Once you have the client, you can perform all the operations that Redis provides.

To close the connection, simply call:

1	client.quit()

Storing and Retrieving Key-Value Pairs

To store a key-value pair in Redis, use the set() method:

1	client.set("<key>", "<value>")

For example:

1 2	client.set("name", "Flavio") client.set("age", 37)

If you run KEYS * in redis-cli on a clean Redis server, you will see the two keys appearing:

To retrieve the value stored in a key, use the get() method:

1	const value = await client.get("name")

To delete a key-value pair, use the del() method:

1	client.del("names")

Working with Lists

In Redis, you can work with lists using the following commands provided by the client object:

lPush
rPush
lTrim
lRange

To create a list, use the lPush() method:

1	client.lPush('names', 'Flavio')

To push a new item to the bottom of the list, use the rPush() method:

1	client.rPush('names', 'Roger')

To add an item at the top of the list, use the lPush() method:

1	client.lPush('names', 'Syd')

To list all the items in a list, use the lRange() method:

1 2	const result = await client.lRange('names', 0, -1) // result is [ 'Roger', 'Flavio', 'Syd' ]

To drop items from a list, use the rPop() method:

1	client.rPop('names')

To delete a list, use the del() method:

1	client.del('names')

Working with Sets

In Redis, you can work with sets using the following commands provided by the client object:

sAdd
sPop
sMembers.

To create a set, use the sAdd() method:

1	client.sAdd('names', 'Flavio')

To add more items to the set, use the sAdd() method:

1	client.sAdd('names', 'Roger')

You can add multiple items at once using the sAdd() method:

1	client.sAdd('names', 'Roger', 'Syd')

You can also pass an array to add multiple items:

1 2	const names = ['Flavio', 'Roger', 'Syd'] client.sAdd('names', names)

To list all the items in a set, use the sMembers() method:

1	const names = await client.sMembers('names')

To drop a random item from a set, use the sPop() method:

1	client.sPop('names')

You can add a second parameter to drop multiple random items:

1	client.sPop('names', 3)

To delete a set, use the del() method:

1	client.del('names')

Working with Hashes

In Redis, you can work with hashes using the following commands provided by the client object:

hSet
hGetAll
hSet
hIncrBy

To create a hash, use the hSet() method:

1	client.hSet('person:1', 'name', 'Flavio', 'age', 37)

To get all the properties of a user, use the hGetAll() method:

1	const items = client.hGetAll('person:1')

To update a hash property, use the hSet() method:

1	client.hSet('person:1', 'age', 38)

To increment a value stored in a hash, use the hIncrBy() method:

1	client.hIncrBy('person:1', 'age', 1)

To delete a hash, use the del() method:

1	client.del('person:1')

Subscriptions

Subscriptions are an amazing feature of Redis that allow us to do really fancy things in Node.js.

A publisher sends a message on a channel and multiple subscribers receive it.

To subscribe to a channel, use the subscribe() method:

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await subscriber.subscribe('dogs', (message) => {
 console.log(message);
})

To publish a message on a channel, use the client.publish('<channel>', '<message>') method:

1	client.publish('dogs', 'Roger')

Please note that you cannot publish and subscribe using the same client instance.

To do so in the same app, create 2 clients:

const subscriber = redis.createClient({ ... })
const publisher = redis.createClient({ ... })

await subscriber.subscribe('dogs', (message) => {
 console.log(channel, message);
})

publisher.publish('dogs', 'Roger')

tags: [“Redis”, “Node.js”, “programming”, “database”, “JavaScript”]