oldhaven/app/models/beathaven/playlist.rb

class Playlist < ActiveRecord::Base
  belongs_to :user
  belongs_to :artist
  has_many :playlist_items, dependent: :destroy
  
  def serialize
    data = {name: name, pic_url: pic_url, tracks: []}
    playlist_items.each do |item|
      data[:tracks] << item.track.serialize
    end
    data
  end
end