Mongoose populate find array of ObjectId - node.js

Question

I'm trying to populate an array of ObjectIds when doing a find with Mongoose.
Here is the models/comment.js:
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
// set up a mongoose model
var CommentSchema = new Schema({
comment: {
type: String,
unique: false,
required: true
},
date: {
type: Date,
default: new Date()
},
});
module.exports = mongoose.model('Comment', CommentSchema);
Here is the models/question.js:
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var Comment = require('./comment');
// set up a mongoose model
var QuestionSchema = new Schema({
title: {
type: String,
unique: false,
required: true
},
question: {
type: String,
required: true
},
plus: {
type: Number,
required: true,
default: 0
},
minus: {
type: Number,
required: true,
default: 0
},
date: {
type: Date,
default: new Date()
},
comments:[
{type: Schema.Types.ObjectId, ref: 'Comment'}
]
});
module.exports = mongoose.model('Question', QuestionSchema);
Here is index.js
var express = require('express');
var app = express();
var request = require('request-promise');
var bodyParser = require('body-parser');
var morgan = require('morgan');
var mongoose = require('mongoose');
var passport = require('passport');
var config = require('./config/database'); // get db config file
var User = require('./models/user'); // get the mongoose model
var Room = require('./models/room'); // get the mongoose model
var Comment = require('./models/comment'); // get the mongoose model
var Question = require('./models/question'); // get the mongoose model
var port = process.env.PORT || 5000;
var jwt = require('jwt-simple');
var http = require('http');
var io = require('socket.io');
var server = http.createServer(app);
var io = io.listen(server);
// get our request parameters
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
// log to console
app.use(morgan('dev'));
// Use the passport package in our application
app.use(passport.initialize());
// Set the port
app.set('port', port);
//App files located in /public
app.use(express.static(__dirname + '/public'));
// views is the directory for all template files
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');
// The root url of the website serves the Angular app
app.get('/', function (request, response) {
response.render('pages/index');
});
// connect to database
mongoose.connect(config.database);
// pass passport for configuration
require('./config/passport')(passport);
var roomService = require('./controllers/roomservice.js');
roomService.setup(io);
// connect the api routes under /api/*
app.use('/api', apiRoutes);
// Start the Express app
server.listen(app.get('port'), function () {
console.log('Node app is running on port', app.get('port'));
});
Here is controllers/roomservice.js
function RoomService(){
var socketio;
var Comment = require('../models/comment'); // get the mongoose model
var Question = require('../models/question'); // get the mongoose model
var Room = require('../models/room'); // get the mongoose model
function setup(io){
socketio = io;
socketio.on("connection", function(socket){
socket.on('joinRoom', function(msg){
console.log("joinRoom");
socket.join(msg.room)
Question.find({})
.exec(function(err, questions) {
for(var question in questions){
for(var comment in questions[question].comments){
questions[question].comments[comment] = Comment.find({ "_id": questions[question].comments[comment]});
}
}
socket.emit("listQuestions", questions)
});
});
socket.on('addQuestion', function(msg){
console.log("addQuestion");
var question = new Question({
title: msg.title,
question: msg.question
});
// save the question
question.save(function(err) {
if (err) throw err;
io.to(msg.room).emit("addQuestion", question);
});
});
socket.on('addComment', function(msg){
var comment = new Comment({
comment: msg.comment
});
// save the comment
Question.findOne({_id: msg.question}, function(err, question){
if (err) throw err;
question.comments.push(comment);
question.save(function(err) {
if (err) throw err;
io.to(msg.room).emit("addComment", comment);
console.log(question);
});
});
});
socket.on('addPlus', function(msg){
// save the comment
Question.findOne({_id: msg.question}, function(err, question){
if (err) throw err;
question.plus = question.plus + 1;
question.save(function(err) {
if (err) throw err;
io.to(msg.room).emit("addPlus", question);
});
});
});
socket.on('addMinus', function(msg){
// save the comment
Question.findOne({_id: msg.question}, function(err, question){
if (err) throw err;
question.minus = question.minus + 1;
question.save(function(err) {
if (err) throw err;
io.to(msg.room).emit("addMinus", question);
});
});
});
});
}
return{
setup: setup
}
}
module.exports = new RoomService();
I'm trying to populate the array of comments when returning the list of questions. I tried it with the populate method from Mongoose but it returns an empty array of comments.
Question.find({}).populate("comments")
.exec(function(err, questions) {
socket.emit("questions", questions)
});
When I don't put the populate method I get something like this :
[{"title": "test", "comments": ["1253454", "654654747"]},
{"title": "test", "comments": ["1253454", "654654747"]}]
But I want something like this :
[{"title": "test", "comments": [{"comment": "test"}, {"comment": "test2"}]},
{"title": "test", "comments": [{"comment": "test"}, {"comment": "test2"}]}]
What am I doing wrong?

Answer 1

What is your mongoose version? The version 4.7.1 is fine for me:
import { connDb } from './base';
import { model, Schema, SchemaTypes, disconnect } from 'mongoose';
const Question = model<any>('Question', new Schema({
title : SchemaTypes.String,
comments: [
{
type: SchemaTypes.ObjectId,
ref : 'Comment',
},
],
}))
const Comment = model<any>('Comment', new Schema({
comment: SchemaTypes.String,
}))
connDb().then(() => Promise.all([
Comment.remove({}),
Question.remove({}),
])).then(() => Comment.insertMany([
{
comment: 'hello',
},
{
comment: 'world',
}
])).then((data: any[]) => Question.insertMany([
{
title : 'question',
comments: data.map((item: any) => item._id),
}
])).then(() => Question.find({}).populate('comments').exec()).then((d) => {
console.log(JSON.stringify(d))
}).then(() => disconnect())
The result is:
+ ts-node ./src/__test__/pop_comment.ts
[{"_id":"5846322e69db6c1ec86ac5fd","__v":0,"title":"question","comments":[{"_id":"5846322e69db6c1ec86ac5fb","__v":0,"comment":"hello"},{"_id":"5846322e69db6c1ec86ac5fc","__v":0,"comment":"world"}]}]