Not persistent id in Embedded Document in Mongoid 4

Question

I use Mogoid first time (current beta with Rails-API 4 support). I use it to preserve user forms as one document with embedded documents. In update method in controllers I use this construct to create new card if returned card don't have id

params[:form_cards].andand.each do |card|
  card['form_card_fields'].andand.each do |field|
    if !field['id'].blank?
      @formField=@formCard.form_card_fields.find(field['id'])
    else
      @formField=@formCard.form_card_fields.create!
  end
end

if @form.save
  render json: @form, status: :created, location: @form
else
  render json: @form.errors, status: :unprocessable_entity
end

It works in most cases. Unfortunatelly, sometimes something wrong happend and my created embedded document don't have persistent id, whenever I read it, result is different. After using

Example returned ID (each one is from different read operation for the same field)

536615c94d6163d0010a0000
536615d64d6163d0010b0000
536615dd4d6163d0010c0000
536615e84d6163d0010d0000
536616014d6163d0010e0000

My models looks like that:

class Form
  include Mongoid::Document
  include Mongoid::Timestamps

  embeds_many :form_cards
end

class FormCard
  include Mongoid::Document
  include Mongoid::Timestamps

  embeds_many :form_card_fields
  embedded_in :form

end

class FormCardField
  include Mongoid::Document
  include Mongoid::Timestamps

  embedded_in :form_card

end

I suppose it is some kind of persistence error but I can't find root cause...

I would be glad if whoever can help me cause it bugs me for three days

Answer 1

add cascade_callbacks: true after the embeds_many or embeds_one so the models should look like the following

class Form
  ...
  embeds_many :form_cards, cascade_callbacks: true
  ...
end

class FormCard
  ...
  embeds_many :form_card_fields, cascade_callbacks: true
  ...
end

the cascade_callbacks allow running the callbacks of the embedded docs... so that persisting a parent persists it's embedded docs.