Nested Mongoose asynchronous functions

Question

Nested Mongoose asynchronous functions

I need to iterate in an array looking for items and then sum those prices.

It's a problem of asynchronous functions. I'm using Q to help me with promises, but I can't solve this situation.

var price = 0;

var setPrice = function() {
    _.each(order.items, function(item) {
        Item.findOne({ 'shortname': item.item }).exec().then(function(doc) {
            price += doc.price;
        });
    });
}

Q.nfcall(setPrice).then(function() {
    console.log(price);
}

Price is set to 0, nfcall runs the setPrice function that iterate and sum prices and then, the "then" function should show the total price, but it doesn't.

How can I solve this situation?

javascript
node.js
asynchronous
mongoose
q

Answer 1

Instead of trying to find them one by one, why not return all of them at once.

Item.where('shortname'.in(order.items).execute(function(err,docs) {
  //in here you can do your summation, and the rest of your code. 
  var price = 0;
  for(var i=0;i<docs.length;i++) {
    price += docs[i].price;
  }
});