middleware-cache

$ npm install --save middleware-cache

Overview

The middleware cache is a higher order component that stores the results of an express middleware function in a repository so that repetitive long running calls can be made more efficient.

For examples of repositories you can use, checkout this repo. Node Repositories

Most likely you will want to use an in-memory cache or a redis cache. Caching in something like mongo will require you to invalidate the cache on your own.

Options

• key: string or hash function to determine where to store in db. note that this should be namespaced for the middleware type.
• selector: function to pick the resulting cacheable data out of the ORIGINAL middleware result.

Usage

// pass the data store into the cache function
const cache = require('middleware-cache')(repo);

const middleware = (req, res, next) => {
  res.locals.complete = true;
  setTimeout(next, 500);
};

const options = {
  key: (req, res) => `orderHistory|${req.user._id}`,
  expire: 1000 // the repository implements this, so for redis it is in seconds
};

const cachedMiddleware = cache('orderHistory', middleware, options);

app.use(cachedMiddleware);
app.get('/foo', cachedMiddleware, (req, res) => res.send({}));

Prior Art

leahciMic/cache-middleware