Redis + node.js render a list of objects

Question

Redis + node.js render a list of objects

I'm experimenting with node.js and redis, and I managed to get a few functions to render single objects using Mustache as a template engine.

Now I'm a situation where I need to render items from a list, looking like this

list:$(id) = [node_id_1, node_id_2, node_id_3]

node:$(id) = {"value1":1, "value2":2, "value3":3, "value4":4 }

This is the way I work with the values

//get the list of nodes
redis.lrange('list:' + req.param.list_id, 0,-1, function(err, lastNode){

  //request the parameters i need from the single node
  var request = ['id','type'];
  redis.hmget('node:' + lastNode, request, function(err, node){
     //operations on the node
  });
});

Now I want to render these nodes. But I'm not sure what's the best way to do it. Shall I save everything inside a js array and count to make sure the render function get called after all the nodes being read?

Probably it's really trivial but I'm not sure since it's the first time I work with redis and node

Thanks,k.

node.js
redis
mustache

Answer 1

This is indeed a little tricky in asynchronous land. I recommend the async module, which, among other things, can map an array to an asynchronous function:

Something like:

// [nodeIds] = [1, 2, 3]
async.map(nodeIds, getNode, function (err, nodes) {
    // render nodes
});

function getNode (node, next) {
    redis.hmget('node' + node, ['id', 'type'], next);
}

Note, though, that hmget will return an array with values, which may or may not be what you want to render in a view. If an object would be more suitable, you could try hgetall.