redis-cache

Simple cache using Redis. It uses Redis' EXPIRE command to set key expiry times, so you don't have to worry about checking cache validity.

All methods return a promise. The module is written in ES2015, but the module's package.json points to the transpiled version, so you can use it in ES5.

This module is designed to be used with node-redis. node-redis is not a dependency of this module, allowing you more freedom in the way you use it.

Install

npm Install redis-cache-simple

Usage

var RedisCache = require('redis-cache-simple').RedisCache;
var redisClient = require('redis').createClient();

// override the default 'expire' value (in seconds)
var cache = new RedisCache(redisClient, { 'expire': 300 });

// Setting a key
cache.set('some-key', 'some value').then(function() {
	console.log('Key set');
});

// Getting a key
// Note: You can also use get(). It is identical
cache.fetch('some-key').then(function(value) {
	console.log('Key value: %s', value);
});

The default options are as follows:

var DEFAULT_OPTIONS = {
	'expire': 60 * 60, // 1hr
	'json': true,
	'rejectOnNull': false,
	'prefix': null
};

• expire: The key expiry time in seconds
• json: If true, stringify and parse JSON values
• rejectOnNull: If true, rejects instead of resolves on null values from fetch()
• prefix: An optional string to prefix all keys with

Methods

RedisCache.fetch(key) and RedisCache.get(key)

fetch() is exactly the same as get()

Fetches (gets) a key by its name from the cache.

cache.fetch('some-key')
	.then(function(value) {
		// do something with the value
	}).

RedisCache.set(key, value, options = {})

Sets a key in the cache. options can be any of the accepted options and will override said option for this call only.

cache.set('some-key', 'some-value')
	.then(function() {
		// key set
	})
	.catch(function(err) {
		// something went wrong when setting the key
	});

RedisCache.del(key)

Deletes a key from the cache.

cache.del('some-key')
	.then(function(reply) {
		// reply = the number of keys that were removed
	})
	.catch(function(err) {
		// something went wrong when removing the key
	});

RedisCache.ttl(key)

Get the remaining Time-To-Live (TTL) for the key. If options.rejectOnNull is true, the promise will be rejected if the key does not exist.

cache.ttl('some-key')
	.then(function(ttl) {
		// tll in seconds
		// ttl is -1 if key exists but has no expire
	})
	.catch(function(err) {
		// something went wrong when getting the key's ttl
	});

RedisCache.exists(key)

Returns true if the key exists, false otherwise.

cache.exists('some-key')
	.then(function(exists) {
		// do something with it
	})
	.catch(function(err) {
		// something went wrong
	});

RedisCache.expire(key, expire)

Set the expiry time for a key in the cache. If expire is not given, the method uses options.expire.

cache.expire('some-key', 120) // expire after 2 minutes
	.then(function() {
		// it worked
	})
	.catch(function(err) {
		// something went wrong
	});

RedisCache.persist(key)

Remove the expiry time on a key, persisting it in the cache.

cache.persist('some-key')
	.then(function() {
		// it worked
	})
	.catch(function(err) {
		// something went wrong
	});

RedisCache.split(options, useDefaultOptions)

Returns a new RedisCache instance sharing the same Redis client. options accepts all the default options. If useDefaultOptions is true, the method uses RedisCache's default options. If false, the new instance inherits its options from this instance.

// override 'expire' and use 'cache's options instead of the default
var cache2 = cache.split({ 'expire': 300 }, false);

Changelog

• v0.0.4 - 27 January 2016
  • Updated repository link in package.json
• v0.0.1 - v0.0.3 - 4 January 2016
  • (0.0.3) Add updated ES5 file
  • (0.0.2) Improved readme
  • (0.0.2) Added RedisCache.split()
  • (0.0.2) RedisCache.ttl() now rejects if rejectOnNull is true and the key does not exist
  • (0.0.2) Fixed extend error
  • (0.0.1) Published on npm
  • (0.0.1) First release

License

Copyright 2016 Michiel van der Velde.

This software is licensed under the MIT License.