A module to make Express interact with Redis (create, get, delete). You can automatically cache all your most popular routes in Redis.
npm install @lindblad/express-redis-cacheexpress-redis-cache
===
Easily cache pages of your app using Express and Redis. Could be used without Express too.
express-redis-cache ships with a CLI utility you can invoke from the console. In order to use it, install express-redis-cache globally (might require super user privileges):
js
var app = express();
var cache = require('express-redis-cache')();
// replace
app.get('/',
function (req, res) { ... });
// by
app.get('/',
cache.route(),
function (req, res) { ... });
`
This will check if there is a cache entry for this route. If not. it will cache it and serve the cache next time route is called.
Redis connection info
By default, redis-express-cache connects to Redis using localhost as host and nothing as port (using Redis default port 6379). To use different port or host, declare them when you require express-redis-cache. If your Redis server requires password, use the auth_pass option.
`js
var cache = require('express-redis-cache')({
host: String, port: Number, auth_pass: REDIS_PASSWORD
});
`
You can pass a Redis client as well:
`js
require('express-redis-cache')({ client: require('redis').createClient() })
`
You can have several clients if you want to serve from more than one Redis server:
`js
var cache = require('express-redis-cache');
var client1 = cache({ host: "...", port: "..." });
var client2 = cache({ host: "...", port: "..." });
...
`
Redis Unavailability
Should the redis become unavailable, the express-redis-cache object will emit errors but will not crash the app. Express.js requests during this time will be bypass cache and will return fresh data.
Once the redis recovers, the caching will begin working again. See example code in the /example folder.
Name of the cache entry
By default, the cache entry name will be default prefix:name where name's value defaults to req.originalUrl.
`js
app.get('/',
cache.route(), // cache entry name is cache.prefix + "/"
function (req, res) { ... });
`
You can specify a custom name like this:
`js
app.get('/',
cache.route('home'), // cache entry name is now cache.prefix + "home"
function (req, res) { ... });
`
You can also use the object syntax:
`js
app.get('/',
cache.route({ name: 'home' }), // cache entry name is cache.prefix + "home"
function (req, res) { ... });
`
Also, you can use res.express_redis_cache_name to specify the name of the entry such as:
`js
app.get('/user/:userid',
// middleware to define cache name
function (req, res, next) {
// set cache name
res.express_redis_cache_name = 'user-' + req.params.userid;
next();
},
// cache middleware
cache.route(),
// content middleware
function (req, res) {
res.render('user');
}
);
`
Conditional caching
You can also use a previous middleware to set whether or not to use the cache by using res.use_express_redis_cache:
`js
app.get('/user',
// middleware to decide if using cache
function (req, res, next) {
// Use only cache if user not signed in
res.use_express_redis_cache = ! req.signedCookies.user;
next();
}.
cache.route(), // this will be skipped if user is signed in
function (req, res) {
res.render('user');
}
);
`
Prefix
All entry names are prepended by a prefix. Prefix is set when calling the Constructor.
`js
// Set default prefix to "test". All entry names will begin by "test:"
var cache = require('express-redis-cache')({ prefix: 'test' });
`
To know the prefix:
`js
console.log('prefix', cache.prefix);
`
You can pass a custom prefix when calling route():
`js
app.get('/index.html',
cache.route('index', { prefix: 'test' }), // force prefix to be "test", entry name will be "test:index"
function (req, res) { ... });
`
You can also choose not to use prefixes:
`js
app.get('/index.html',
cache.route({ prefix: false }), // no prefixing, entry name will be "/index.html"
function (req, res) { ... });
`
Expiration
Unless specified otherwise when calling the Constructor, cache entries don't expire. You can specify a default lifetime when calling the constructor:
`js
// Set default lifetime to 60 seconds for all entries
var cache = require('express-redis-cache')({ expire: 60 });
`
You can overwrite the default lifetime when calling route():
`js
app.get('/index.html',
cache.route({ expire: 5000 }), // cache entry will live 5000 seconds
function (req, res) { ... });
// You can also use the number sugar syntax
cache.route(5000);
// Or
cache.route('index', 5000);
// Or
cache.route({ prefix: 'test' }, 5000);
`
You can also provide a hash of status code / expiration values if you for example want to retry much sooner in failure cases (403/404/500/etc). Status ranges can be specified via 4xx/5xx. You must provide a default value (xxx). The most specific rule will be used. For example, if the status code is 200, and there are expirations set for 200, 2xx, and xxx, the expiration for 200 will be used.
`js
app.get('/index.html',
cache.route({
expire: {
200: 5000,
4xx: 10,
403: 5000,
5xx: 10,
xxx: 1
}
}),
function (req, res) { ... });
`
You can also specify
Content Type
You can use express-redis-cache to cache HTML pages, CSS stylesheets, JSON objects, anything really. Content-types are saved along the cache body and are retrieved using res._headers['content-type']. If you want to overwrite that, you can pass a custom type.
`js
app.get('/index.html',
cache.route({ type: 'text/plain' }), // force entry type to be "text/plain"
function (req, res) { ... });
`
Events
The module emits the following events:
error
You can catch errors by adding a listener:
`js
cache.on('error', function (error) {
throw new Error('Cache error!');
});
`
message
express-redis-cache logs some information at runtime. You can access it like this:
`js
cache.on('message', function (message) {
// ...
});
`
connected
Emitted when the client is connected (or re-connected) to Redis server
`js
cache.on('connected', function () {
// ....
});
`
disconnected
Emitted when the client is disconnected from Redis server. When (and if) it reconnects, it will emit a 'connected' event again
`js
cache.on('disconnected', function () {
// ....
});
`
Note You can get the connexion status at any time by getting the property cache.connected which returns a boolean (true = connected, false = disconnected).
deprecated
Warning emitted when stumbled upon a deprecated part of the code
`js
cache.on('deprecated', function (deprecated) {
console.log('deprecated warning', {
type: deprecated.type,
name: deprecated.name,
substitute: deprecated.substitute,
file: deprecated.file,
line: deprecated.line
});
});
`
The Entry Model
This is the object synopsis we use to represent a cache entry:
`js
var entry = {
body: String // the content of the cache
touched: Number // last time cache was set (created or updated) as a Unix timestamp
expire: Number // the seconds cache entry lives (-1 if does not expire)
type: String // the content-type
};
`
The module
The module exposes a function which instantiates a new instance of a class called ExpressRedisCache.
`js
// This
var cache = require('express-redis-cache')({ / ... / });
// is the same than
var cache = new (require('express-redis-cache/lib/ExpressRedisCache'))({ / ... / });
`
The constructor
As stated above, call the function exposed by the module to create a new instance of ExpressRedisCache,
`js
var cache = require('express-redis-cache')(/* Object | Undefined / options);
`
Where options is an object that has the following properties:
| Option | Type | Default | Description |
| ------------- |----------|-------|----------|--------|
| host | String | undefined | Redis server host
| port | Number | undefined | Redis server port
| prefix | String | require('express-redis-cache/package.json').config.prefix | Default prefix (This will be prepended to all entry names) |
| expire | Number | undefined | Default life time of entries in seconds |
| client | RedisClient | require('redis').createClient({ host: cache.host, port: cache.port }) | A Redis client |
API
The route method is designed to integrate easily with Express. You can also define your own caching logics using the other methos of the API shown below.
get Get cache entries
`js
cache.get(/ Mixed (optional) / query, / Function( Error, [Entry] ) / callback );
`
To get all cache entries:
`js
cache.get(function (error, entries) {
if ( error ) throw error;
entries.forEach(console.log.bind(console));
});
`
To get a specific entry:
`js
cache.get('home', function (error, entries) {});
`
To get a specific entry for a given prefix:
`js
cache.get({ name: 'home', prefix: 'test' }, function (error, entries) {});
`
You can use wildcard:
`js
cache.get('user*', function (error, entries) {});
`
add Add a new cache entry
`js
cache.add(/ String / name, / String / body, / Object (optional) / options, /* Function( Error, Entry ) / callback )
`
Where options is an object that can have the following properties:
- expire Number (lifetime of entry in seconds)
- type String (the content-type)
Example:
`js
cache.add('user:info', JSON.stringify({ id: 1, email: 'john@doe.com' }), { expire: 60 60 24, type: 'json' },
function (error, added) {});
`
del Delete a cache entry
`js
cache.del(/ String / name, / Function ( Error, Number deletions ) / callback);
`
You can use wildcard (*) in name.
size Get cache size for all entries
`js
cache.size(/* Function ( Error, Number bytes ) /);
`
Command line
We ship with a CLI. You can invoke it like this: express-redis-cache
View cache entries
`bash
express-redis-cache ls
`
Add cache entry
`bash
express-redis-cache add $name $body $expire --type $type
`
$3
`bash
Cache simple text
express-redis-cache add "test" "This is a test";
Cache a file
express-redis-cache add "home" "$(cat index.html)";
Cache a JSON object
express-redis-cache add "user1:location" '{ "lat": 4.7453, "lng": -31.332 }' --type json;
Cache a text that will expire in one hour
express-redis-cache add "offer" "everything 25% off for the next hour" $(( 60 * 60 ));
`
Get single cache entry
`bash
express-redis-cache get $name
Example: express-redis-cache get user1:*
Output:
`
Delete cache entry
`bash
express-redis-cache del $name
Example: express-redis-cache del user1:*
Output:
`
Get total cache size
`bash
express-redis-cache size
Output:
`
Example Code
Run the example to see how the caching behaves. You can kill the redis-server and the application will respond with non-cached information.
`
npm install
cd example
node example.js
`
Test
We use Mocha and Should for the tests. You can invoke tests like this:
npm test
Test environments
You can specify the following environments before running your tests:
`bash
export EX_RE_CA_HOST="";
export EX_RE_CA_PORT="";
export EX_RE_CA_PREFIX="";
``