Mongoose

'use strict';

var mongoose = require('mongoose'),
    Schema = mongoose.Schema,
    User = require('../user/user.model');

var ChatMessageSchema = new Schema({
  content: String,
  authorId: String,
  date: { type: Date, default: Date.now }
});

ChatMessageSchema
.virtual('authorUserName')
.get(function(){
  var username = User.findById(this.authorId, function(err, user){
    if (err) console.err(err);
    //PROBLEM TUTAJ
  });
  return username;
});

module.exports = mongoose.model('ChatMessage', ChatMessageSchema);