deferred.resolve() is not iterating the last element inside a forloop - angularjs

Question

in the model.findone i'm getting a array which consists of 3 elements. In the else part i'm looping through each item & fetching offering head of that particular item.
But i'm able to get only 2 offering heads.Not able to fetch the last offering head.
Is there any problem with my code??
function getOfferingsHeads(id) {
var deferred = Q.defer();
var offeringHeads = [];
model
.findOne({ _id: id })
.exec(function (err, item) {
if(err) {
console.log(err);
deferred.reject(err);
}
else {
// deferred.resolve(item.offerings);
// var offeringsList = [];
// offeringsList = item.offerings;
for (var i = 0; i < item.offerings.length; i++) {
executivesModel
.findOne({offName: item.offerings[i] })
.exec(function(err1, item1) {
if(err1){
console.log(err1);
deferred.reject(err1);
}
else{
offeringHeads.push(item1.offHead);
deferred.resolve(offeringHeads);
}
});
}
}
});
return deferred.promise;
}

Answer 1

You can't resolve a deferred more than once, and in general you shouldn't be using deferreds at all. Since mongoose has a promise-friendly API, you should just use that. It will make your code much much cleaner:
function getOfferingHead(offName) {
return executivesModel
.findOne({offName: offName })
.exec()
.then(function (item) {
return item.offHead;
});
}
function getOfferingsHeads(id) {
return model
.findOne({ _id: id })
.exec()
.then(function (item) {
return Q.all(item.offerings.map(getOfferingHead));
});
}
To use the function:
getOfferingsHeads('myId').then(function (heads) {
console.log(heads);
});

Answer 2

Not sure this is what you intended but you are resolving the same promise more than once.
The latest version of mongoose lets you set the Promise library to use.
Here's a correction to what I believe you meant to do:
//Somewhere near mongoose definition
mongoose.Promise = require('q').Promise;
function getOfferingsHeads(id) {
var offeringHeads = [];
return model
.findOne({ _id: id })
.then(function (item) {
if(!item) {
//Handle no results
return Q.reject()
}
else {
return Q.all(item.offerings.map(function(offering){
executivesModel
.findOne({offName: offering.name})
}));
}
});
}
//Now you can use
getOfferingsHeads('someId').then(function (offerings) {
...
});