I have document that has embedded document wich may embed itself .

Main model:

class FrameType
  include Mongoid::Document
  include Mongoid::Timestamps
  
  field :name, :type => String
  field :key, :type => String
  
  embeds_many :slot_definitions, :as => :slot_definition_container
  
  accepts_nested_attributes_for :slot_definitions, :allow_destroy => true
    
end

Nested model:

class SlotDefinition
  include Mongoid::Document
  
  field :name, :type => String
  field :key, :type => String
  
  embedded_in :slot_definition_container, :polymorphic => true
end

Class that inherits SlotDefinition model:

class SlotDefinitionArray < SlotDefinition
  embeds_one :slot_definition, :as => :slot_definition_container
  
  accepts_nested_attributes_for :slot_definition
end

`

I'm trying to update Frame and put there SlotDefinition with embedded slot definition:

frame_type.update_attributes({"name"=>"3D Object", "key"=>"object","slot_definitions_attributes"=>{"0"=>

, "1315315562427"=>{"_type"=>"SlotDefinitionArray", "name"=>"Materials", "key"=>"materials", "slot_definition_attributes"=>

, "_destroy"=>"false"}}})

and I see this log message in my log:

wikimedical_development['frame_types'].update(

, {"$pushAll"=>{"slot_definitions"=>[{"_type"=>"SlotDefinitionArray", "name"=>"Materials", "key"=>"materials", "_id"=>BSON::ObjectId('4e6622c0cf6c125bef000010'), "slot_definition"=>{"_type"=>"SlotDefinitionFrame", "name"=>"material", "key"=>"material", "frame_type_id"=>"4e65f4eccf6c124af6000012", "_id"=>BSON::ObjectId('4e6622c0cf6c125bef000011')}}]}, "$set"=>{"slot_definitions.slot_definition"=>

}})

So mongoid tries to perform 2 operations in mongo for 1 update - $pushAll and $set