express-memjs-cache

This is an Express middleware that caches responses using the MemJS memcached client.

Installation

0. Set up your Express project

1. Install the express-memjs-cache npm package:

   npm install express-memjs-cache

2. Add the Memcachier Heroku add-on to your app

Setup

Place the middleware before your Express response handler(s):

const express = require('express')
const cache = require('express-memjs-cache')
const app = express()
  .use(cache({ cacheMaxAge: 60 }))
  .get('/widgets', expensiveListWidgets)

In this arrangement, responses will be cached using the URI (request.originalUrl, which includes the query string) as the cache key. The first request will miss the cache and set the cache key to the sent response body. Subsequent requests to the same URL will "hit" the cache and respond with the cached response body until the cached entry's age is at or above the cacheMaxAge (in this case, 60 seconds).

Cache keys

The default cache key of the request.originalUrl should serve most uses cases, but you can customize the cache key in a couple of different ways to suit your needs.

Regardless of how you do it, you will need to calculate the cache key before the cache middleware runs. The cache needs the cache key to determine whether it can serve the request, but it also needs the your handler(s) to generate a response body to cache.

1. Provide your own getCacheKey option as a function that takes the Express request and response objects as arguments and returns a string.

2. Set the x-cache-key response header. As with a custom getCacheKey function, you will need to set this header in a handler or middleware before the cache.