then-redis

then-redis

then-redis is a small, promise-based Redis client for node.js. It supports all the features of Redis in a simple, user-friendly package.

The two major differences between then-redis and node_redis are:

1. then-redis returns a CommonJS Promises/A+ promise when you issue a command
2. The entire codebase is very small (~300 LOC), just like Redis

then-redis gets out of your way as much as possible. Command arguments and return values are exactly what you see in Redis' Command Reference*.

then-redis uses pipelining to issue all commands. This means that commands are issued over the socket connection as quickly as possible, and that subsequent commands do not need to wait to find out the result of previous commands before they are issued. Of course, if you need to find out the result of a previous command first, just use then (see the examples below).

* MSET, MSETNX, HMSET and HGETALL optionally accept/return JavaScript objects for convenience in dealing with Redis' multi-key and hash APIs

Usage

All of the usage examples assume the following:

var redis = require('then-redis');

To create a client:

var db = redis.createClient();
var db = redis.createClient('tcp://localhost:6379');
var db = redis.createClient({
  host: 'localhost',
  port: 6379
});

If you need to use AUTH or SELECT you can include them in the auth segment of your URL or in the password and database properties of an object literal.

var db = redis.createClient('tcp://1:password@localhost:6379');
var db = redis.createClient({
  host: 'localhost',
  port: 6379,
  database: 1,
  password: 'password'
});

Once you have a client, you're ready to issue some commands. All Redis commands are present on the redis.Client prototype and may be called with variable length argument lists.

// Simple set, incrby, and get
db.set('my-key', 1);
db.incrby('my-key', 5);
db.get('my-key').then(function (value) {
  assert.strictEqual(value, 6);
});

// Multi-key set/get
db.mset({ a: 'one', b: 'two' });
db.mget('a', 'b').then(function (values) {
  assert.deepEqual(values, [ 'one', 'two' ]);
});

// Sets
db.sadd('my-set', 1, 2, 3);
db.sismember('my-set', 2).then(function (value) {
  assert.strictEqual(value, 1);
});

// Hashes
var originalHash = { a: 'one', b: 'two' };
db.hmset('my-hash', originalHash);
db.hgetall('my-hash').then(function (hash) {
  assert.deepEqual(hash, originalHash);
});

// Transactions
db.multi();
db.incr('first-key');
db.incr('second-key');
db.exec().then(function (reply) {
  assert.deepEqual(reply, [ 1, 1 ]);
});

// Pubsub
var subscriber = redis.createClient();
subscriber.on('message', function (channel, message) {
  console.log('Received message: ' + message);
});
subscriber.subscribe('my-channel').then(function () {
  db.publish('my-channel', 'a message');
});

If you don't like the variable-length argument lists, or you already have an array of arguments that you need to pass to a command, you can always call client.send() directly. It takes two arguments: 1) the name of the Redis command and 2) an array of command arguments.

db.send('get', [ 'my-key' ]);
db.send('incrby', [ 'my-key', 5 ]);
db.send('mset', [ 'a', 'one', 'b', 'two' ]);

When you create a client without explicitly calling client.connect() it will try to automatically establish a connection the first time you issue a command. While it's waiting for the connection to be established it will buffer all commands and then flush them in the correct order once the socket is open. This works beautifully most of the time (all the specs are written in this style), but it will throw if your connection fails for some reason.

To be sure you have a good connection to the database before issuing any commands, call client.connect() or use the high-level redis.connect(options) method to create a client and connect in one call. Use then to wait for the response from Redis before continuing.

// Create a separate client instance and connect() it.
var db = redis.createClient(options);
db.connect().then(function () {
  db.get('my-key');
}, function (error) {
  console.log('Failed to connect to Redis: ' + error);
});

// Or use redis.connect() to do both in one call.
redis.connect(options).then(function (db) {
  db.get('my-key');
}, function (error) {
  console.log('Failed to connect to Redis: ' + error);
});

The specs also have lots of good usage examples.

Testing

To run the tests:

$ redis-server --port 6379
$ npm install
$ npm test

License

Copyright 2013 Michael Jackson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.