playing with mongoid save vs changed vs array relations

save_test.rb

require 'mongoid'

Mongoid.configure do |config|
  config.clients.default = {
    hosts: ['localhost:27017'],
    database: 'junk_db',
  }
  config.raise_not_found_error = false
end

class Kitty
  include Mongoid::Document
  field :name, type: String

  belongs_to :cat
end

class Cat
  include Mongoid::Document

  field :just_an_array, type: Array
  has_many :kitties,
           before_add: :before_add_kittie, after_add: :after_add_kittie
           #, after_remove: :after_remove_kittie
  def before_add_kittie(kitty)
    puts "before_add_kittie kitties param: #{kitty.name} changed: #{self.changed?} self.kitties #{ self.kitties.map(&:name) }"
  end
  def after_add_kittie(kitty)
    puts "after_add_kittie kitties param: #{kitty.name} changed: #{self.changed?} self.kitties #{ self.kitties.map(&:name) }"
  end
end

logger = Logger.new(STDOUT)
logger.level = :debug
Mongoid.logger = logger
Mongo::Logger.logger = logger


Cat.collection.drop
mom = Cat.new
puts "new doc mom.changed? #{mom.changed?}"
mom.save
puts "saved doc mom.changed? #{mom.changed?}"

mom.just_an_array = [1]
puts "mom new just_an_array mom.changed? #{mom.changed?}"
mom.save
puts "saved doc mom.changed? #{mom.changed?}"
mom.just_an_array << 2
puts "mom new element 2 in just_an_array mom.changed? #{mom.changed?}"
mom.save
puts "saved doc mom.changed? #{mom.changed?}"



kit1 = Kitty.new(name: 'kit1')
kit1.save
kit2 = Kitty.new(name: 'kit2')
kit2.save

puts "mom before adding kit1 mom.changed? #{mom.changed?}"
mom.kitties << kit1
puts "mom added kit1 mom.changed? #{mom.changed?}"
mom.save
puts "saved doc mom.changed? #{mom.changed?}"

puts "mom before assigning [kit2] mom.changed? #{mom.changed?}"
mom.kitties = [kit2]
puts "mom assigned [kit2] mom.changed? #{mom.changed?}"
mom.save
puts "saved doc mom.changed? #{mom.changed?}"


kit3 = Kitty.new(name: 'kit3')
kit3.save
puts "saved kit3 kit3.changed? #{kit3.changed?}"
kit3.cat = mom
puts "assigned mom kit3.changed? #{kit3.changed?}"
kit3.save
puts "saved kit3 kit3.changed? #{kit3.changed?}"