MongooseJS - population path of subdocuments - node.js

Question

I'm having real problems with population on the below schemas. It may not be the best design of models (relatively new to MEAN stacks) but I can get it to populate everything except the Spec model.
// Spec Model
var SpecSchema = new Schema({
time: {
type: Date,
default: Date.now
},
active: {
type: Boolean,
default: 'true'
},
name: String,
desc: String
});
module.exports = mongoose.model('Spec', SpecSchema);
// Thing model
var specsSchema = new Schema({
time: {
type: Date,
default: Date.now
},
spec: {
type: Schema.Types.ObjectId,
ref: 'Spec'
},
value: String,
});
var ThingSchema = new Schema({
time: {
type: Date,
default: Date.now
},
active: {
type: Boolean,
default: true
},
title: String,
specs: [specsSchema]
});
var Thing = mongoose.model('Thing', ThingSchema);
// Set model
var thingsSchema = new Schema({
time: {
type: Date,
default: Date.now
},
active: {
type: Boolean,
default: 'true'
},
thing: {
type: Schema.Types.ObjectId,
ref: 'Thing'
}
});
var SetSchema = new Schema({
user: {
type: Schema.Types.ObjectId,
ref: 'User'
},
time: {
type: Date,
default: Date.now
},
active: {
type: Boolean,
default: 'true'
},
title: String,
things: [thingsSchema]
});
var Set = mongoose.model('Set', SetSchema);
The standard population is fine but i cant for the life of me get the model.populate to work and from all the examples and solutions I have looked at I'm unclear as to what the path should be.
Set.findById(req.params.id)
.populate('things.thing')
.populate('user', '_id name')
.exec(function (err, set) {
if(err) { return handleError(res, err); }
if(!set) { return res.send(404); }
Thing.populate(set,{
path:'things.thing.specs.spec',
select: 'name',
model: Spec
}, function(err, set){
if ( err ) return res.json(400, err);
});
return res.json(set);
});
any pointers in the right direction would be much appreciated.

Answer 1

path:'things.thing.specs.spec',
select: 'name',
model: Spec
should be
path:'things.thing.specs.spec',
select: 'name',
model: 'Spec'