cachegoose-events

Mongoose caching that actually works.

About

A Mongoose caching module that works exactly how you would expect it to, with the latest version of Mongoose. This version is a fork of the original cachegoose module by boblauer, but also adds the on, off, once and emit functions of the EventEmitter

Usage

const mongoose = require('mongoose');
const cachegoose = require('cachegoose');

cachegoose(mongoose, {
  engine: 'redis',    /* If you don't specify the redis engine,      */
  port: 6379,         /* the query results will be cached in memory. */
  host: 'localhost'
});

Record
  .find({ some_condition: true })
  .cache(30) // The number of seconds to cache the query.  Defaults to 60 seconds.
  .exec(function(err, records) {
    ...
  });

Record
  .aggregate()
  .group({ total: { $sum: '$some_field' } })
  .cache(0) // Explicitly passing in 0 will cache the results indefinitely.
  .exec(function(err, aggResults) {
    ...
  });

You can also pass a custom key into the .cache() method, which you can then use later to clear the cached content.

var mongoose = require('mongoose');
var cachegoose = require('cachegoose');

cachegoose(mongoose, {
  engine: 'redis',
  port: 6379,
  host: 'localhost'
});

var userId = '1234567890';

Children
  .find({ parentId: userId })
  .cache(0, userId + '-children') /* Will create a redis entry          */
  .exec(function(err, records) {  /* with the key '1234567890-children' */
    ...
  });

ChildrenSchema.post('save', function(child) {
  // Clear the parent's cache, since a new child has been added.
  cachegoose.clearCache(child.parentId + '-children');
});

Insert .cache() into the queries you want to cache, and they will be cached. Works with select, lean, sort, and anything else that will modify the results of a query.

Clearing the cache

If you want to clear the cache for a specific query, you must specify the cache key yourself:

function getChildrenByParentId(parentId, cb) {
    Children.find({ parentId })
        .cache(0, `${parentId}_children`)
        .exec(cb)
}

function clearChildrenByParentIdCache(parentId, cb) {
    cachegoose.clearCache(`${parentId}_children`, cb)
}

If you call cachegoose.clearCache(null, cb) without passing a cache key as the first parameter, the entire cache will be cleared for all queries.

Listening to cache events

This fork adds four events to cachegoose, which can be listened to from the cachegoose.cache

cachegoose.cache.on('get', key => {
    console.log(`${key} was fetched from cache`)
})

cachegoose.cache.on('set', key => {
    console.log(`${key} was set in cache`)
})

cachegoose.cache.on('del', key => {
    console.log(`${key} was deleted from cache`)
})

cachegoose.cache.on('clear', () => {
    console.log('Cache was cleared')
})

Caching populated documents

When a document is returned from the cache, cachegoose will hydrate it, which initializes it's virtuals/methods. Hydrating a populated document will discard any populated fields (see Automattic/mongoose#4727). To cache populated documents without losing child documents, you must use .lean(), however if you do this you will not be able to use any virtuals/methods (it will be a plain object).

Test

npm test

monbrey/cachegoose-events