Redis is a fast and efficient in-memory key-value store. It is also known as a data structure server, as the keys can contain strings, lists, sets, hashes and other data structures. If you are using Node.js, you can use the node_redis module to interact with Redis. This tutorial explains various ways of interacting with Redis from a Node.js app using the node_redis library.

node_redis, as you may have guessed, is the Redis client for Node.js. You can install it via npm using the following command.

[code]
npm install redis
[/code]

Once you have installed node_redis module you are good to go. Let’s create a simple file, app.js, and see how to connect with Redis from Node.js.

[js]
var redis = require(‘redis’);
var client = redis.createClient(); //creates a new client
[/js]

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:

[js]
var client = redis.createClient(port, host);
[/js]

Now, you can perform some action once a connection has been established. Basically, you just need to listen for connect events as shown below.

[js]
client.on(‘connect’, function() {
console.log(‘connected’);
});
[/js]

So, the following snippet goes into app.js:

[js]
var redis = require(‘redis’);
var client = redis.createClient();

client.on(‘connect’, function() {
console.log(‘connected’);
});
[/js]

Now, type node app in the terminal to run the app. Make sure your Redis server is up and running before running this snippet.

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

All the Redis commands are exposed as different functions on the client object. To store a simple string use the following syntax:

[js]
client.set(‘framework’, ‘AngularJS’);
[/js]

Or

[js]
client.set([‘framework’, ‘AngularJS’]);
[/js]

The above snippets store a simple string AngularJS against the key framework. You should note that both the snippets do the same thing. The only difference is that the first one passes a variable number of arguments while the later passes an args array to client.set() function. You can also pass an optional callback to get a notification when the operation is complete:

[js]
client.set(‘framework’, ‘AngularJS’, function(err, reply) {
console.log(reply);
});
[/js]

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