CODEWITHSUNDEEP
node.jsasynchronous
user2598794
user2598794

Reputation: 727

Async Waterfall function only call the first callback

I'm trying to play a bit with node and async waterfall function. This is my code:

var async = require('async');

var waterfall = function (req, res) {
    async.waterfall([
        _function1(req),
        _function2,
        _function3
    ], function (error, success) {
        if (error) { alert('Something is wrong!'); }
        console.log("success");
        return alert('Done!');
    });
};

function _function1 (req) {
    return function (callback) {
        var something = req.body;
        console.log("first");
        callback (null, something);
   }
}

function _function2 (something, callback) {
    return function (callback) {
      console.log("second");
       var somethingelse = function () {  };
       callback (err, somethingelse);
    }
}

function _function3 (something, callback) {
    return function (callback) {
      console.log("third");
      var somethingmore = function () { };
      callback (err, somethingmore);
    }
}

waterfall(function(){}, function(){});

But in the output I get only 'first'. Why another callbacks are not called?

Upvotes: 0

Views: 1001

Answers (1)

robertklep
robertklep

Reputation: 203241

You shouldn't return a function from _function2 and _function3. The reason it's being done for _function1 is to pass req in (which can be done in better ways, see below):

function _function2 (something, callback) {
  console.log("second");
  var somethingelse = function () {  };
  callback (err, somethingelse);
}

function _function3 (something, callback) {
  console.log("third");
  var somethingmore = function () { };
  callback (err, somethingmore);
}

To get req into the waterfall, you could use this:

async.waterfall([
    function(callback) { return callback(null, req); },
    _function1,
    _function2,
    _function3
], ...);

Or (which I would prefer):

async.waterfall([
    _function1.bind(this, req),
    _function2,
    _function3
], ...);

In both cases, you wouldn't need to return a function from _function1 either:

function _function1 (req, callback) {
  var something = req.body;
  console.log("first");
  callback (null, something);
}

Upvotes: 1

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