async.js methods inside async.js methods

Question

Disclaimer: new to JS and everything around it. :)

I was wondering if we could nest async functions within one another

I have a waterfall method in node:

/**
 * POST new travel wish
 */
router.post('/add', function(req, res) {
    var db = req.db;

    console.log(req.body);
    // add properties: customer_id and timestamp
    var date = new Date();
    //...

    var notif;

    async.waterfall(
      [
         // find the User
         function(next){
           db.collection(userCollection).findOne({_id: new ObjectId(req.session.userID)}, next);
         },

         // insert a new travelwish
         function(user, next){
           notif = {
             'username': user.username,
           };
           // TODO: add a async.parallel
           db.collection('travelwishlist').insert(req.body, next);
         },

         // setup timer for processing and send confirmation
         function(insertedTravelWish, next){
           NotificationManager.sendConfirmationNotification(notif);
           next(null, insertedTravelWish);         
         }
     ],

       // waterfall callback --> send http response.
       function (err, insertedTravelWish) {                  
         res.send(
           //if everything is ok the system sends the travel wish ID to the client otherwise error
           (err === null) ? { msg: insertedTravelWish[0]["_id"] } : { msg: 'err' }
         );
        }
     );
});

I want to insert multiple items instead of just one.

I think i can do this with parallel, but can I put it inside the existing waterfall?

i donT know.. i thought it d be messy and ppl would suggest a cleaner alternative.. — Orkun
– Orkun, Commented Jan 29, 2015 at 16:03

Danny · Accepted Answer · 2015-01-29 15:39:07Z

1

Yep, you totally can do it, here is some piece of example

async.waterfall([
    function (callback) {
        callback(null, 1);
    },
    function (arg, callback) {
        callback(null, arg1 + 1);
    },
    function (arg, callback) {
        async.parallel([
            function (_callback) { ... },
            function (_callback) { ... },
        ], finalCallback);
    }
]);

just a little tip, make sure you proivde different names for the callbacks (so you won't call the other one) if I've 2 nested functions that requires a callback most of the time I name them as callback _callback __callback

edited Jan 29, 2015 at 15:39

answered Jan 29, 2015 at 12:47

Danny

8812 gold badges10 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Orkun Over a year ago

cool! But, about the callbacks, why donT u make the changes in your answer? callback --> _callback

Danny Over a year ago

@Zortkun, I was sure its clear enough, there is many examples on async's github page. anyway the _callback should be the arg in the inside parallel functions.

Collectives™ on Stack Overflow

async.js methods inside async.js methods

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related