Can't get Mongoose.js Subdocument Array to populate

Question

Can't get Mongoose.js Subdocument Array to populate

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

node.js
mongodb
mongoose

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)

Answer 3

Follow-up on @JohnnyHK's post, you can specify the Model to use in poplulate() for now: https://github.com/LearnBoost/mongoose/issues/1377#issuecomment-15920370

Answer 4

I have something that looks a slightly different but populates the document with the array items. I'm wondering if it's the objectid's that are causing the issues.

var mongoose = require('mongoose');
var Schema = mongoose.Schema, ObjectID = Schema.ObjectId;

var SubSchema = new Schema({
    testsub: String,       
    created: { type: Date, default: Date.now }
});

var MainSchema = new Schema({
    test: String
    subs: [SubSchema],
    created: { type: Date, default: Date.now }
});

mongoose.model('MainSchema', MainSchema, mainschema);

var query = MainSchema.find({});