Migrating from node_redis

It's not hard to migrate from node_redis to ioredis since ioredis is compatible with node_redis for most APIs. However there are some exceptions:

• constructor. node_redis use var client = redis.createClient() to create a new RedisClient instance, while ioredis prefer to var redis = new Redis(). For compatibility, ioredis supports var redis = Redis.createClient() as well.

• The options passed to the constructor are different. See API#new_Redis.

• ioredis considers null/undefined as empty strings, while node_redis will convert them to "null"/"undefined". For instance:

// node_redis
client.set('foo', null);
client.get('foo', function(_, res) {
  console.log(typeof res, res); // "string", "null"
});

// ioredis
redis.set('foo', null);
redis.get('foo', function(_, res) {
  console.log(typeof res, res); // "string", ""
});

• Transaction. The result of transaction in node_redis and ioredis are different, for instance:

// node_redis
client.multi().set('foo').get('foo').exec(function (err, res) {
  /* err is: 
      [
        [Error: Error: ERR wrong number of arguments for 'set' command],
        [Error: Error: EXECABORT Transaction discarded because of previous errors.]
      ]
     res is undefined
  */
});

// ioredis
redis.multi().set('foo').get('foo').exec(function (err, res) {
  /* err is: { [ReplyError: EXECABORT Transaction discarded because of previous errors.] }
     res is undefined
  */
});


// node_redis
client.multi().set('foo', 'bar').lpush('foo', 1).exec(function (err, res) {
  /* err is: null
     res is [ 'OK', 'WRONGTYPE Operation against a key holding the wrong kind of value' ]
  */
});

// ioredis
redis.multi().set('foo', 'bar').lpush('foo', 1).exec(function (err, res) {
  /* err is: null
     res is [
       [ null, 'OK' ],
       [ { [ReplyError: WRONGTYPE Operation against a key holding the wrong kind of value] } ]
     ]
  */
});

• Pub/Sub. When you subscribe multiple channels in node_redis, only the first response is included in the callback. For instance:

client.subscribe('foo', 'bar', function (err, channel) {
  // channel is 'foo'
  // `bar` isn't subscribed now
});

However, in ioredis, callback function will be invoked only when all the channels are subscribed, and the result is the channel count that the client is subscribed:

redis.subscribe('foo', 'bar', function (err, count) {
  // count is 2
  // both `foo` and `bar` are subscribed now
});