Mongoose embedded documents

Problem.js

var mongoose = require('mongoose');

var problemSchema = new mongoose.Schema({
  event: String,
  problemName: String,
  roundName: String,
  roundId: Number,
  roomId: Number,
  componentId: Number
});

module.exports = mongoose.model('Problem', problemSchema);

User.js

var mongoose = require('mongoose');
var ProblemSchema = require('../models/Problem').Schema;

var userSchema = new mongoose.Schema({
  email: { type: String, unique: true, lowercase: true },
  password: String,
  problems: [ProblemSchema]
});