Node.js Redis Module

Redis is an open-source in-memory data store used for handling various data structures efficiently. It is widely used in modern applications for fast data access.

Can be used as a database, cache, and message broker.
Supports multiple data structures like strings, hashes, sets, and streams.
Improves Node.js application performance by reducing cache size and enabling fast integration.

Prerequisites

Before starting with our application, make sure the following installation is in your system:

An IDE of your choice.
Redis is installed in your system. Check the version that you are using the following command:

redis cli --version

Node.js and NPM are installed and configured in your system.
Basic knowledge of Node.js and Redis.

Implementing Redis Module

Step 1: Initialize the Application

First, initialize the project by creating a package.json file:

npm init

Step 2: Install Redis Module

Install the Redis package using NPM:

npm install redis --save

Step 3: Create Redis Client

Create a file named app.js and add the following code:

Node

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

client.on("connect", () => {
    console.log("Connection Successful!!");
});

client.on("error", (err) => {
    console.log("Redis Error:", err);
});

client.connect();

Here, the Redis module is imported and a Redis client is created.
The connect event confirms a successful connection, while the error event handles connection errors.
The client.connect() method establishes the connection (required in Redis v4).

Step 4: Run the Application

Run the application using:

node app.js

Output:

Connection Successful!!

Storing a String in Redis

To store a string in Redis, write the following code in the app.js file:

Node

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

client.on("connect", () => {
    console.log("Connection Successful!!");
});

client.on("error", (err) => {
    console.log("Redis Error:", err);
});

(async () => {
    await client.connect();

    try {
        const result = await client.set("Intern", "gfg");
        console.log(result);
    } catch (err) {
        console.log(err);
    }
})();

The set() method stores data in key-value format.
Here, Intern is the key and gfg is the value.
In Redis v4, set() returns a promise and logs OK on successful storage.

Output:

Connection Successful!!
OK

Retrieving a String Value

To get the value of the key stored in the Redis database, we will use the get function as shown below:

Node

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

client.on("connect", () => {
    console.log("Connection Successful!!");
});

client.on("error", (err) => {
    console.log("Redis Error:", err);
});

(async () => {
    await client.connect();

    try {
        // Set value
        const result = await client.set("Intern", "gfg");
        console.log(result);

        // Get value
        const value = await client.get("Intern");
        console.log(value);
    } catch (err) {
        console.log(err);
    }
})();

The get() method retrieves the value associated with the specified key and prints it to the console.

Output:

Connection Successful!!
OK
gfg

Storing Objects in Redis (Hash)

To store objects in Redis database, write the following code:

Node

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

client.on("connect", () => {
    console.log("Connection Successful!!");
});

client.on("error", (err) => {
    console.log("Redis Error:", err);
});

(async () => {
    await client.connect();

    try {
        // Store a string
        const result = await client.set("Intern", "gfg");
        console.log(result);

        // Get the string value
        const value = await client.get("Intern");
        console.log(value);

        // Store an object as a hash
        await client.hSet("Interns", {
            pos: "Tech Writer",
            Org: "GFG"
        });
    } catch (err) {
        console.log(err);
    }
})();

Redis hashes store objects as field–value pairs.
Here, Interns is the hash key storing position and organization details.
Now, the key will be Interns and its value will be { pos: "Tech Writer", Org: "GFG" }.

Retrieving Object Values from Redis

To get the value from the Redis database, write the following code:

Node

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

client.on("connect", () => {
    console.log("Connection Successful!!");
});

client.on("error", (err) => {
    console.log("Redis Error:", err);
});

(async () => {
    await client.connect();

    try {
        // Store a string
        const result = await client.set("Intern", "gfg");
        console.log(result);

        // Get the string value
        const value = await client.get("Intern");
        console.log(value);

        // Store an object as a hash
        await client.hSet("Interns", {
            pos: "Tech Writer",
            Org: "GFG"
        });

        // Get all values from the hash
        const data = await client.hGetAll("Interns");
        console.log(data);
    } catch (err) {
        console.log(err);
    }
})();

The hGetAll() method retrieves all field-value pairs from the hash and displays them as an object.

Output:

Connection Successful!!
OK
gfg
{ pos: 'Tech Writer', Org: 'GFG' }

Prerequisites

Implementing Redis Module

Step 1: Initialize the Application

Step 2: Install Redis Module

Step 3: Create Redis Client

Step 4: Run the Application

Storing a String in Redis

Retrieving a String Value

Storing Objects in Redis (Hash)

Retrieving Object Values from Redis

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