Can't get Mongoose.js Subdocument Array to populate

Question

I'm using mongoose.js on a node.js server connecting to mongodb and I have a mongoose model like the following

SubSchema = new Schema({
    _member:     {type: ObjectId, ref: 'Member'},
    members:     [{type: ObjectId, ref: 'Member'}],
    created:     { type: Date, default: Date.now }
});
mongoose.model('SubModel', SubSchema);

MainSchema = new Schema({
    _member:     {type: ObjectId, ref: 'Member'},
    subs:        [SubSchema],
    members:     [{type: ObjectId, ref: 'Member'}],
    created:     { type: Date, default: Date.now }
});
var MainModel mongoose.model('MainModel', MainSchema);

which i pull with a command like this

var q = MainModel.find({})
                 .sort('created', -1)
                 .limit(25)
                 .populate("_member")
                 .populate("subs._member")
                 .populate("subs.members");

q.execFind(function(err, mains){
    //mains[0].subs[0].members - will always be empty why?
});

my problem is that i can't get subs.members array to populate or even load, it just keeps showing as an empty array.

I've tried .populate("subs.members") to no avail even though subs._member loads just fine

Answer 1

try this

    SubSchema = new Schema({
        _member:     {type: ObjectId, ref: 'Member'},
        members:     [{type: ObjectId, ref: 'Member'}],
        created:     { type: Date, default: Date.now }
    });
    var SubModel = mongoose.model('SubModel', SubSchema);//add

    MainSchema = new Schema({
        _member:     {type: ObjectId, ref: 'Member'},
        subs:        [SubSchema],
        members:     [{type: ObjectId, ref: 'Member'}],
        created:     { type: Date, default: Date.now }
    });

    var MainModel = mongoose.model('MainModel', MainSchema);

    MainModel.find({})
             .sort('created', -1)
             .limit(25)
             .populate("_member")
             .populate("subs._member")
             .exec(function(err, mains){

                 //add
                 SubModel.populate(mains,{
                     path:'subs.members'
                 },function(err,mains){
                    //mains[0].subs[0].members - is not empty
                 });
             });

Answer 2

@leesei: I can't comment on your post (too little rep), so I leave this as a separate answer.

In mongoose 3.6 subdoc population still doesn't work, the issue github.com/LearnBoost/mongoose/issues/1381 has been closed 7 months ago with the following solution as a workaround. I had to change it slightly to merge the populated subdocument back to the main document.

The subdocument's model Story has to be specified explicitly:

Person.findById(user1._id).populate("stories")
    .exec(function(err, doc {
         Story.populate(doc.stories, {path: 'creator'}, function (err, stories) {
             doc.stories = stories;
             return doc;
         })
})

In the solution above this works:

Story.populate(doc.stories, {path: 'creator'}, callback)

but this still won't work:

Story.populate(doc, {path: 'stories.creator'}, callback)