cache-express-az v2.0.2

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

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

Hello I am Aawez Khan aawez@nodejs.community Thanks @node-community

Why?

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

Usage

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

Cache a route

import express from 'express'
import cache_express from 'cache-express-az'

let app = express()
let cache = cache_express.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 = cache_express.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 cache_express from 'cache-express-az'
import redis from 'redis'

let app = express()

// if redisClient option is defined, cache_express will use redis client
// instead of built-in memory store
let cacheWithRedis = cache_express.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 cache_express from 'cache-express-az'
let cache = cache_express.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.cache_expressGroup = req.params.collection
  res.json({ success: true })
})

// add route to display cache performance (courtesy of @killdash9)
app.get('/api/cache/performance', (req, res) => {
  res.json(cache_express.getPerformance())
})

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

// add route to manually clear target/group
app.get('/api/cache/clear/:target?', (req, res) => {
  res.json(cache_express.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 = cache_express.options({
  headers: {
    'cache-control': 'no-cache',
  },
}).middleware

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

API

• cache_express.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.
• cache_express.middleware([duration], [toggleMiddleware], [localOptions]) - the actual middleware that will be used in your routes. duration is in the following format "length", 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.
• cache_express.getPerformance() - returns current cache performance (cache hit rate)
• cache_express.getIndex() - returns current cache index of keys
• cache_express.clear([target]) - clears cache target (key or group), or entire cache if no value passed, returns new index.
• cache_express.newInstance([options]) - used to create a new cache_express instance (by default, simply requiring this library shares a common instance)
• cache_express.clone() - used to create a new cache_express instance with the same options as the current one

Available Options (first value is default)

{
  debug:            false|true,     // if true, enables console output
  defaultDuration:  '1 hour',       // should be either a number (in ms) or a string, 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:        fn(req, res),   // appendKey takes the req/res objects and returns a custom value to extend the cache key
  headerBlacklist:  [],             // list of headers that should never be cached
  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)
  },
  trackPerformance: false,          // enable/disable performance tracking... WARNING: super cool feature, but may cause memory overhead issues
  headers: {
    // 'cache-control':  'no-cache' // example of header overwrite
  },
  respectCacheControl: false|true   // If true, 'Cache-Control: no-cache' in the request header will bypass the cache.
}

*Optional: Typescript Types (courtesy of @danielsogl)

$ npm install -D @types/cache_express

Custom Cache Keys

Sometimes you need custom keys (e.g. save routes per-session, or per method). We've made it easy!

Note: All req/res attributes used in the generation of the key must have been set previously (upstream). The entire route logic block is skipped on future cache hits so it can't rely on those params.

cache_express.options({
  appendKey: (req, res) => req.method + res.session.id,
})

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.cache_expressGroup = [somevalue]; to your route enables this. See example below:

var cache_express = require('cache-express-az')
var cache = cache_express.middleware

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

// POST collection/id
app.post('/api/:collection/:id?', function(req, res, next) {
  // update model
  cache_express.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 cache_express index (for the curious)
app.get('/api/cache/index', function(req, res, next) {
  res.send(cache_express.getIndex())
})

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

Debugging/Console Out

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

$ export DEBUG=cache_express
$ export DEBUG=cache_express,othermoduleThatDebugModuleWillPickUp,etc

By setting internal option

import cache-express-az from 'cache-express-az'

cache_express.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-cache_express-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.