CODEWITHSUNDEEP
node.jsredis
RikyTres
RikyTres

Reputation: 676

Async NodeJS request to Redis db

I need to do several request to Redis db, and I need the response from a request to do the next one.

Let's analyze this example: (I'm using node_redis for the requests)

var message-id = undefined;

// request the next id
client.incr("message-id", function(err, id) {
    message-id = id;
});

// use the 'next id' for storing a message
client.hmset("messages", message-id, messageContent);

This way doesn't work, because message-id id still undefined when I call client.hmdet().

The following is the lazy way, and it consist in put the client.hmdet() inside the client.incr() callback. var message-id = undefined;

// request the next id
client.incr("message-id", function(err, id) {
    message-id = id;

    // use the 'next id' for storing a message
    client.hmset("messages", message-id, messageContent, function(){
        //more request here
    });
});

I think this is not a good way to proceed, because if I have lots chained request, I need to put each request inside its previous request callback, and this will create a block of code hard to maintain.

I'm interested in the best practices for doing lots of request asynchronously. Can someone advise me?

Upvotes: 0

Views: 782

Answers (1)

alfonsodev
alfonsodev

Reputation: 2754

I recommend you to have a look to the async module, it implements several patterns that you can use. your example async waterfall 

async.waterfall([
    function(callback){
        callback(null, 'one', 'two');
    },
    function(arg1, arg2, callback){
        callback(null, 'three');
    },
    function(arg1, callback){
        // arg1 now equals 'three'
        callback(null, 'done');
    }
], function (err, result) {
   // result now equals 'done'    
});

And also if you want to explore other possibilities beyond the callback pattern, you have the q module that implements promises A+

Upvotes: 1

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