I have an <code>after_create</code> callback for one of my embedded models which updates data in the model (well, it queues up a background job but in dev/test it all happens in serial). When the identity map is enabled, the data does not persist if I <code>concat</code> or <code><<</code> the embedded model into the parent but does persist when I use <code>create</code>.

Example:

class Book
  include Mongoid::Document
  embeds_many :pages
end

class Page
  include Mongoid::Document
  embedded_in :book
  field :text
  
  after_create :update_something
  
  def update_something
    update_attributes(:text => "test")
  end
end

# Ensure that we have an empty identity map
Mongoid::IdentityMap.clear
Book.destroy_all

b = Book.create
b.pages << Page.new
b.pages
# => [#<Page _id: ...>]

# Clear out the identity map to ensure the next find call hits the database
Mongoid::IdentityMap.clear
Book.find(b.id).pages
# => []
# would have expected this to contain a Page

If I change <code>b.pages << Page.new</code> to <code>b.pages.create</code>, everything works fine. Alternatively, I can call <code>Mongoid::IdentityMap.clear</code> in the callback and it'll work regardless of how the create occurs.

Using Mongoid 2.3.0.