A simple API response caching middleware for Express/Node using plain-english durations.

Supports Redis or built-in memory engine with auto-clearing.

Why?

Because route-caching of simple data/responses should ALSO be simple.

Installation

npm install apicache

Dependencies

None

Usage

To use, simply inject the middleware (example: apicache.middleware('5 minutes', [optionalMiddlewareToggle])) into your routes. Everything else is automagic.

Cache a route

import express from 'express'
import apicache from 'apicache'

let app = express()
let cache = apicache.middleware

app.get('/api/collection/:id?', cache('5 minutes'), (req, res) => {
  // do some work... this will only occur once per 5 minutes
  res.json({ foo: 'bar' })
})

Cache all routes

let cache = apicache.middleware

app.use(cache('5 minutes'))

app.get('/will-be-cached', (req, res) => {
  res.json({ success: true })
})

Use with Redis

import express from 'express'
import apicache from 'apicache'
import redis from 'redis'

let app = express()

// if redisClient option is defined, apicache will use redis client
// instead of built-in memory store
let cacheWithRedis = apicache
                      .options({ redisClient: redis.createClient() })
                      .middleware

app.get('/will-be-cached', cacheWithRedis('5 minutes'), (req, res) => {
  res.json({ success: true })
})

Cache grouping and manual controls

import apicache from 'apicache'
let cache = apicache.middleware

app.use(cache('5 minutes'))

// routes are automatically added to index, but may be further added
// to groups for quick deleting of collections
app.get('/api/:collection/:item?', (req, res) => {
  req.apicacheGroup = req.params.collection
  res.json({ success: true })
})

// add route to display cache index
app.get('/api/cache/index', (req, res) => {
  res.json(apicache.getIndex())
})

// add route to manually clear target/group
app.get('/api/cache/clear/:target?', (req, res) => {
  res.json(apicache.clear(req.params.target))
})

/*

GET /api/foo/bar --> caches entry at /api/foo/bar and adds a group called 'foo' to index
GET /api/cache/index --> displays index
GET /api/cache/clear/foo --> clears all cached entries for 'foo' group/collection

*/

Use with middleware toggle for fine control

// higher-order function returns false for responses of other status codes (e.g. 403, 404, 500, etc)
const onlyStatus200 = (req, res) => res.statusCode === 200

const cacheSuccesses = cache('5 minutes', onlyStatus200)

app.get('/api/missing', cacheSuccesses, (req, res) => {
  res.status(404).json({ results: 'will not be cached' })
})

app.get('/api/found', cacheSuccesses, (req, res) => {
  res.json({ results: 'will be cached' })
})

Prevent cache-control header "max-age" from automatically being set to expiration age

let cache = apicache.options({
              headers: {
                'cache-control': 'no-cache'
              }
            })
            .middleware

let cache5min = cache('5 min') // continue to use normally

API

• apicache.options([globalOptions]) - getter/setter for global options. If used as a setter, this function is chainable, allowing you to do things such as... say... return the middleware.
• apicache.middleware([duration], [toggleMiddleware], [localOptions]) - the actual middleware that will be used in your routes. duration is in the following format "[length] [unit]", as in "10 minutes" or "1 day". A second param is a middleware toggle function, accepting request and response params, and must return truthy to enable cache for the request. Third param is the options that will override global ones and affect this middleware only.
• middleware.options([localOptions]) - getter/setter for middleware-specific options that will override global ones.
• apicache.getIndex() - returns current cache index [of keys]
• apicache.clear([target]) - clears cache target (key or group), or entire cache if no value passed, returns new index.
• apicache.newInstance([options]) - used to create a new ApiCache instance (by default, simply requiring this library shares a common instance)
• apicache.clone() - used to create a new ApiCache instance with the same options as the current one

Available Options (first value is default)

{
  debug:            false|true,     // if true, enables console output
  defaultDuration:  3600000,        // should be a number (in ms), defaults to 1 hour
  enabled:          true|false,     // if false, turns off caching globally (useful on dev)
  redisClient:      client,         // if provided, uses the [node-redis](https://github.com/NodeRedis/node_redis) client instead of [memory-cache](https://github.com/ptarjan/node-cache)
  appendKey:        [],             // if you want the key (which is the URL) to be appended by something in the req object, put req properties here that point to what you want appended. I.E. req.session.id would be ['session', 'id']
  statusCodes: {
    exclude:        [],             // list status codes to specifically exclude (e.g. [404, 403] cache all responses unless they had a 404 or 403 status)
    include:        [],             // list status codes to require (e.g. [200] caches ONLY responses with a success/200 code)
  },
  headers: {
    // 'cache-control':  'no-cache' // example of header overwrite
  }
}

Cache Key Groups

Oftentimes it benefits us to group cache entries, for example, by collection (in an API). This would enable us to clear all cached "post" requests if we updated something in the "post" collection for instance. Adding a simple req.apicacheGroup = [somevalue]; to your route enables this. See example below:

var apicache  = require('apicache')
var cache     = apicache.middleware

// GET collection/id
app.get('/api/:collection/:id?', cache('1 hour'), function(req, res, next) {
  req.apicacheGroup = req.params.collection
  // do some work
  res.send({ foo: 'bar' })
});

// POST collection/id
app.post('/api/:collection/:id?', function(req, res, next) {
  // update model
  apicache.clear(req.params.collection)
  res.send('added a new item, so the cache has been cleared')
});

Additionally, you could add manual cache control to the previous project with routes such as these:

// GET apicache index (for the curious)
app.get('/api/cache/index', function(req, res, next) {
  res.send(apicache.getIndex());
});

// GET apicache index (for the curious)
app.get('/api/cache/clear/:key?', function(req, res, next) {
  res.send(200, apicache.clear(req.params.key || req.query.key));
});

Debugging/Console Out

Using Node environment variables (plays nicely with the hugely popular debug module)

$ export DEBUG=apicache
$ export DEBUG=apicache,othermoduleThatDebugModuleWillPickUp,etc

By setting internal option

import apicache from 'apicache'

apicache.options({ debug: true })

Client-Side Bypass

When sharing GET routes between admin and public sites, you'll likely want the routes to be cached from your public client, but NOT cached when from the admin client. This is achieved by sending a "x-apicache-bypass": true header along with the requst from the admin. The presence of this header flag will bypass the cache, ensuring you aren't looking at stale data.

Contributors

Special thanks to all those that use this library and report issues, but especially to the following active users that have helped add to the core functionality!

• @svozza - added restify tests, test suite refactor, and fixed header issue with restify. Node v7 + Restify v5 conflict resolution, etc, etc. Triple thanks!!!
• @rutgernation - JSONP support
• @enricsangra - added x-apicache-force-fetch header
• @tskillian - custom appendKey path support
• @agolden - Content-Encoding preservation (for gzip, etc)
• @davidyang - express 4+ compatibility
• @nmors - redis support
• @maytis, @ashwinnaidu - redis expiration
• @killdash9 - restify support and response accumulator method
• @ubergesundheit - Corrected buffer accumulation using res.write with Buffers
• @danielsogl - Keeping dev deps up to date
• @peteboere - Node v7 headers update
• @vectart - Added middleware local options support

Bugfixes

• @Amhri, @Webcascade, @conmarap, @cjfurelid, @scambier, @lukechilds, @Red-Lv

Documentation

• @gesposito, @viebel

Changelog

• v0.4.0 - dropped lodash and memory-cache external dependencies, and bumped node version requirements to 4.0.0+ to allow Object.assign native support
• v0.5.0 - updated internals to use res.end instead of res.send/res.json/res.jsonp, allowing for any response type, adds redis tests
• v0.6.0 - removed final dependency (debug) and updated README
• v0.7.0 - internally sets cache-control/max-age headers of response object
• v0.8.0 - modifies response accumulation (thanks @killdash9) to support res.write + res.end accumulation, allowing integration with restify. Adds gzip support (Node v4.3.2+ now required) and tests.
• v0.8.1 - fixed restify support and added appropriate tests (thanks @svozza)
• v0.8.2 - test suite and mock API refactor (thanks @svozza)
• v0.8.3 - added tests for x-apicache-bypass and x-apicache-force-fetch (legacy) and fixed a bug in the latter (thanks @Red-Lv)
• v0.8.4 - corrected buffer accumulation, with test support (thanks @ubergesundheit)
• v0.8.5 - dev dependencies update (thanks @danielsogl)
• v0.8.6, v0.8.7 - README update
• v0.8.8 - corrected to use node v7+ headers (thanks @peteboere)
• v0.9.0 - corrected Node v7.7 & v8 conflicts with restify (huge thanks to @svozza for chasing this down and fixing upstream in restify itself). Added coveralls. Added middleware.localOptions support (thanks @vectart). Added ability to overwrite/embed headers (e.g. "cache-control": "no-cache") through options.