Rails Callback

Callback

Do something before, after model operations

• before_validation
• after_validation
• before_save
• around_save
• before_create
• before_update
• before_destroy
• after_create
• after_update
• after_save
• after_find
• after_initialize

create/update/destroy

create, create!, decrement, destroy
destroy!, destroy_all, increment!, save
save!, toggle!, update, update_attribute, valid?

after_find

all, first, find, find_by, find_by_sql, last

after_initialize

new

Example

class Review < ActiveRecord::Base
  after_destroy :log_history
  
  private
  def log_history
     logger.info('deleted:' +  self.inspect)
  end
end
&#91;/ruby&#93;
basically, call back should be defined as private

<h3>Condition<h3>
[ruby]
after_destroy :log_histroy, unless: Proc.new { |r| r.name == "great" }

block callback

class Review < ActiveRecord::Base
  after_destroy do |r|
    logger.info('deleted: ' + r.inspect)
  end
end
&#91;/ruby&#93;

<h3>Create callback class</h3>
Example
[ruby]
class ReviewCallbacks
  cattr_accessor :logger
  self.logger ||= Rails.logger
  
  def after_destroy(r)
     logger.info('deleted: ' + r.inspect)
  end
end

class Review < ActiveRecord::Base after_destroy ReviewCallbacks.new end [/ruby]