Returning results from a series of callback functions in Node.Js

Question

I have an exports function in my Node.Js / Express app, which I want to return a certain value obtained through a series of callback functions inside of it. Trying to make it work for several hours but can't find the right way... Maybe you can help? Here's the code:

exports.finalResult = function() {

    var finalanswer = firstFunction(secondFunction);

    function firstFunction(callback) {
        dbneo.cypherQuery(context_query, function(err, cypherAnswer) {

            if (err) {
                err.type = 'neo4j';
                return callback(err);
            }
            var notion = 1;
            // Probably this return below doesn't work because it's inside of a db query function...
            return callback(null, notion);

        });

    }

    function secondFunction(err, notion) {
        if (err) console.log(err);
        var answer = notion + 1
        return answer;
    }

    return finalanswer;

}

and then I call from another file this exports function to obtain a result like

 console.log(options.finalResult());

but it returns undefined.

Please, help!

micnic · Accepted Answer · 2014-05-28 11:01:17Z

2

exports.finalResult = function(finalCallback) {

    var finalanswer = firstFunction(secondFunction);

    function firstFunction(callback) {
        dbneo.cypherQuery(context_query, function(err, cypherAnswer) {

            if (err) {
                err.type = 'neo4j';
                return callback(err);
            }
            var notion = 1;
            callback(null, notion);
        });
    }

    function secondFunction(err, notion) {
        if (err) console.log(err);
        var answer = notion + 1
        finalCallback(answer);
    }
}

// Usage
options.finalResult(function (result) {
    console.log(result);
});

answered May 28, 2014 at 11:01

micnic

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