Автоматический update связей many-to-many в MongoDB (Mongoose) ?

var User = new mongoose.Schema({
  venue: {
    type: [mongoose.Schema.Types.ObjectId],
    ref: 'Site'
  }
}

var Site = new mongoose.Schema({
  user: {
    type: [mongoose.Schema.Types.ObjectId],
    ref: 'User'
  }
}