nodejs redis Q promises, how to make it work?

Question

nodejs redis Q promises, how to make it work?

I am trying to get few values from redis, combine them and eventually send. But I just can't make those promises work.

This is the simple get functions from redis

client.get('user:1:id',function(err,data){
    // here I have data which contains user ID
});
client.get('user:1:username',function(err,data){
    // here I have data which contains username
});

Now I want to get ID and username and send them, but I have no idea how to make that work. I manage to make it work with callbacks but it is very messy result, so then i tried to wrap anonymous functions into Q.fcall and after call .then which looks something like that

client.get('user:1:id',Q.fcall(function(err,data){
    return data;
}).then(function(val) {
   // do something
}));

but that gives me error for too many arguments been passed and I'm not even sure if that would help me even if it would work.

node.js
redis
promise
q

Answer 1

Q.all([Q.ninvoke(client, 'get', 'user:1:id'),
       Q.ninvoke(client, 'get', 'user:1:username')]).then(function (data) {
  var id = data[0];
  var username = data[1];
  // do something with them
});

See https://github.com/kriskowal/q#adapting-node

Answer 2

I use a simple RequireJS module using node-redis and whenjs to create a lifted redis wrapper:

define [
  'redis/lib/commands'
  'when'
  'when/node/function'
], (Commands, When, NodeFn) ->
  'use strict'

  lift = (redis) ->
    wrapped = {}
    Commands.map (cmd) ->
      wrapped[cmd] = (args...) ->
        def = When.defer()
        args.push NodeFn.createCallback def.resolver
        redis[cmd].apply redis, args
        def.promise
    wrapped

  {lift}

Usage is straightforward:

client = lift redis.createClient()
client.get("hello").then console.log, console.error