$unwind nested document and $match - node.js

Question

I have a nested document which looks like:
var User = new Schema({
id: String,
position: [{
title: String,
applied:[{
candidate_id: String,
name: String
}],
}],
What I am looking to do is return all of the 'applied' subdocuments which match a certain 'candidate_id'
What I have so far:
app.get('/applied', function(req, res){
var position = "58dc2bd4e7208a3ea143959e";
User.aggregate(
{$unwind : "$position"},
{$unwind : "$position.applied"},
{$match:{'position.applied.candidate_id': position}}).exec(function (err, result) {
console.log(result);
});
res.render('applied', { title: 'applied',layout:'candidate'});
});
I have another function which returns all the positions that match, and that code works:
app.post('/search', function (req, res) {
var position = new RegExp(req.body.position, 'i');
var location = new RegExp(req.body.location, 'i');
User.aggregate(
{$unwind : "$position"},
{$match:{'position.title': position,'position.location':location}}).exec(function (err, result) {
console.log(result);
res.send({ results: result });
});
});
So basically I am struggling with getting a sub-sub-document. Any idea where I'm going wrong?
Sample data:
{
"_id" : ObjectId("58c2871414cd3d209abf5fc9"),
"position" : [
{
"_id" : ObjectId("58d6b7e11e793c9a506ffe8f"),
"title" : "Software Engineer",
"applied" : [
{
"candidate_id" : "58d153e97e3317291gd80087",
"name" : "Sample user"
},
{
"candidate_id" : "58d153e97e3317291fd99001",
"name" : "Sample User2"
}
]
},
{
"_id" : ObjectId("58c2871414cd3d209abf5fc0"),
"title" : "Software Engineer",
}
],
}
What is going on above is there 2 positions, one of which (first entry) has 2 applied candidates, What I need to do is return the nested object if it matches the mongoose query.

Answer 1

Your code seems fine to me I have implemented same and it works for me only possible issue can be that your position="58dc2bd4e7208a3ea143959e" it might be talking it as a string just convert it to objectId by using the following code and check it should work for you.
var mongoose = require('mongoose');
var position = mongoose.Types.ObjectId("58dc2bd4e7208a3ea143959e");
User.aggregate(
{$unwind : "$position"},
{$unwind : "$position.applied"},
{$match:{'position.applied.candidate_id': position}}).exec(function (err, result) {
console.log(result);
});
res.render('applied', { title: 'applied',layout:'candidate'});
});