alien-node-redis-utils

Helper functions for Redis cache on NodeJS. The functions are pure and curried with Ramda.

Install

$ npm install alien-node-redis-utils --save

Run the specs

$ npm test

Methods

getItem

Get an item from the Redis store, provided a recognized cacheKey

 
var redis       = require('redis'),
    redisClient = redis.createClient(),
    cacheUtils  = require('alien-node-redis-utils')(redisClient);
    
cacheUtils.getItem('someKey')
  .then(function(item) {
    // cool
  })
  .catch(function(err) {
    // no item found matching cacheKey
  });

setItem

Set an item in the Redis store. Adds if key does not exist, otherwise updates the cache.

 
var redis       = require('redis'),
    redisClient = redis.createClient(),
    cacheUtils  = require('alien-node-redis-utils')(redisClient);
    
var TWO_HOURS_IN_SECONDS_CACHE_EXPIRE = 1000 * 60 * 60 * 2;
 
var cacheKey = 'someKey', 
    data     = { foo : 'bar' };
    
cacheUtils.setItem(cacheKey, TWO_HOURS_IN_SECONDS_CACHE_EXPIRE, data);
  .then(function(data) {
    // cool
  });

deleteItem

Delete an item from the Redis store, provided a recognized cacheKey

 
var redis       = require('redis'),
    redisClient = redis.createClient(),
    cacheUtils  = require('alien-node-redis-utils')(redisClient);
 
cacheUtils.deleteItem('someKey')
  .then(function() {
    // cool
  })
  .catch(function(err) {
    // some err from redisClient
  });

Helpers

maybeAddToQueryCache

Checks for an existing record matching cacheKey and appends/prepends item

 
var User = require('/path/to/user/model'),
    data = {name : 'joe'};
 
var redis       = require('redis'),
    redisClient = redis.createClient(),
    cacheUtils  = require('alien-node-redis-utils')(redisClient);
 
var CACHE_KEY    = 'api.users',
    CACHE_EXPIRE = 1000 * 60 * 60 * 24;
 
return User.create(data).then(function(user) {
  return cacheUtils.maybeAddToQueryCache(CACHE_KEY, CACHE_EXPIRE, user);
});

pluckFromQueryCache

Checks for an existing record matching cacheKey, looks for an item matching a provided identifierProperty, removes the item and resets the cache.

 
var User = require('/path/to/user/model'),
    data = {id : 123};
 
var redis       = require('redis'),
    redisClient = redis.createClient(),
    cacheUtils  = require('alien-node-redis-utils')(redisClient);
 
var CACHE_KEY   = 'api.users';
 
return User.delete(data)
  .thenResolve(data)
  .then(cacheUtils.pluckFromQueryCache(CACHE_KEY, 'id');

setOrDeleteCacheBucket

Checks for an existing record matching cacheKey, and sets it to items if items is a populated list. If items is falsy or an empty array, cacheKey will be deleted.

 
// See internal usage from pluckFromQueryCache method: 
 
var pluckFromQueryCache = R.curry(function(redisClient, cacheKey, identifierProperty, item) {
  return getItem(redisClient, cacheKey)
    .then(JSON.parse)
    .then(R.defaultTo([]))
    .then(listUtils.filterOutObject(identifierProperty, R.prop(identifierProperty, item)))
    .then(setOrDeleteCacheBucket(redisClient, cacheKey))
    .thenResolve(item)
    .catch(R.always(item));
});

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