Mongoose populate issue - array object - node.js

Question

My schema is as below
Sectionschema
var SectionSchema = new Schema({
name: String,
documents : {
type : [{
type: Schema.ObjectId,
ref: 'Document'
}]
}
}
}
DocumentSchema
var DocumentSchema = new Schema({
name: String,
extension: String,
access: String, //private,public
folderName : String,
bucketName : String,
desc: String
});
Api.js
exports.section = function(req, res, next, id) {
var fieldSelection = {
_id: 1,
name: 1,
documents : 1
};
var populateArray = [];
populateArray.push('documents');
Section.findOne({
_id: id
}, fieldSelection)
.populate(populateArray)
.exec(function(err, section) {
if (err) return next(err);
if (!section) return next(new Error('Failed to load Section ' + id));
// Found the section!! Set it in request context.
req.section = section;
next();
});
}
If I go this way, I have
the 'documents' object is []. However if I remove, "populateArray.push('documents');" then I get documents:['5adfsadf525sdfsdfsdfssdfsd'] -- some object Id (atleast)
Please let me know the way I need to populate.
Thanks.

Answer 1

Change your query to
Section.findOne({
_id: id
}, fieldSelection)
.populate('documents.type')
.exec(function(err, section) {
if (err) return next(err);
if (!section) return next(new Error('Failed to load Section ' + id));
// Found the section!! Set it in request context.
req.section = section;
next();
});
and this works. You need to give the path to populate.

Answer 2

If you just want "documents" in your schema pointing to Array of ObjectID which you will populate later. then you can use this.
var SectionSchema = new Schema({
name: String,
documents : [{
type: Schema.ObjectId,
ref: 'Document'
}]
});
And use the following to populate it
Section.findOne({
_id: id
}, fieldSelection)
.populate('documents')
.exec(function(err, section) {
if (err) return next(err);
if (!section) return next(new Error('Failed to load Section ' + id));
// Found the section!! Set it in request context.
req.section = section;
next();
});