Creation method in Mongoose.js, alternative to custom constructor or hooks

mongoose-article-model.js

'use strict';

/**
 * Module dependencies.
 */
var mongoose = require('mongoose'),
 Schema = mongoose.Schema;

/**
 * Article Schema
 */
var ArticleSchema = new Schema({
 created: {
  type: Date,
  default: Date.now
 },
 title: {
  type: String,
  default: '',
  trim: true,
  required: 'Title cannot be blank'
 },
 url: {
  type: String,
  trim: true,
  default: '',
  required: 'Url cannot be blank'
 },
 content: {
  type: String,
  default: '',
  trim: true
 },
 user: {
  type: Schema.ObjectId,
  ref: 'User'
 }
});

mongoose.model('Article', ArticleSchema);