callbacks

Mongoid supports the following callbacks:

• after_initialize
• before_validation
• after_validation
• before_create
• around_create
• after_create
• before_update
• around_update
• after_update
• before_save
• around_save
• after_save
• before_destroy
• around_destroy
• after_destroy

Callbacks are available on any document, whether it is embedded within another document or not. Note that to be efficient, Mongoid only fires the callback of the document that the persistence action was executed on. This is that Mongoid aims to support large hierarchies and to handle optimized atomic updates callbacks can't be firing all over the document hierarchy.

class Article
  include Mongoid::Document
  field :name, type: String
  field :body, type: String
  field :slug, type: String

  before_create :generate_slug

  protected
  def generate_slug
    self.slug = name.to_permalink
  end
end

Callbacks are coming from ActiveModel, so you can use the new syntax as well:

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

  set_callback(:save, :before) do |document|
    document.generate_slug
  end

  protected
  def generate_slug
    self.slug = name.to_permalink
  end
end