Update parent timestamps when embedded mongoid docs modified

touch_parents_on_modify.rb

module TouchParentsOnModify
  def update(attributes={})
    touch_parents
    super attributes
  end

  def save(options={})
    touch_parents
    super options
  end

  def destroy(options={})
    touch_parents
    super options
  end

  def touch(field=nil)
    touch_parents
    super field
  end
  private

  def touch_parents
    parent = _parent
    while parent do
      parent.touch if respond_to? :updated_at=
      parent = parent._parent
    end
  end
end


# Some mongoid documents using the module

class MyDoc
  include Mongoid::Document
  include Mongoid::Timestamps
  field :name, default: 'my_name'
  embeds_many :my_embedded_docs
end

class MyEmbeddedDoc
  include Mongoid::Document
  include Mongoid::Timestamps
  prepend TouchParentsOnModify          #NOTE: prepend the module, NOT include
  field :name, default: 'embedded'
  embeds_many :my_deep_embedded_docs
  embedded_in :my_doc
end

class MyDeepEmbeddedDoc
  include Mongoid::Document
  include Mongoid::Timestamps
  prepend TouchParentsOnModify
  field :name, default: 'deep embedded'
  embedded_in :my_embedded_doc
end