Sequelize polymorphism example

polymorphism.js

this.Comment = this.sequelize.define('comment', {
  title: Sequelize.STRING,
  commentable: Sequelize.STRING,
  commentable_id: Sequelize.INTEGER
});

this.Comment.prototype.getItem = function() {
  return this['get' + this.get('commentable').substr(0, 1).toUpperCase() + this.get('commentable').substr(1)]();
};

this.Post.hasMany(this.Comment, {
  foreignKey: 'commentable_id',
  constraints: false,
  scope: {
    commentable: 'post'
  }
});

this.Comment.belongsTo(this.Post, {
  foreignKey: 'commentable_id',
  constraints: false,
  as: 'post'
});

this.Photo.hasMany(this.Comment, {
  foreignKey: 'commentable_id',
  constraints: false,
  scope: {
    commentable: 'photo'
  }
});

this.Comment.belongsTo(this.Photo, {
  foreignKey: 'commentable_id',
  constraints: false,
  as: 'photo'
});