.. _callbacks:

*********
Callbacks
*********

.. default-domain:: woop

.. contents:: On this page
   :local:
   :backlinks: none
   :depth: 2
   :class: singlecol

CouchbaseOrm implements many of the `ActiveRecord callbacks
<https://guides.rubyonrails.org/active_record_callbacks.html>`_.


Document Callbacks
==================

CouchbaseOrm supports the following callbacks for documents:

-  ``after_initialize``
-  ``after_build``
-  ``before_validation``
-  ``after_validation``
-  ``before_create``
-  ``around_create``
-  ``after_create``
-  ``after_find``
-  ``before_update``
-  ``around_update``
-  ``after_update``
-  ``before_upsert``
-  ``around_upsert``
-  ``after_upsert``
-  ``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, CouchbaseOrm only invokes
the callback on the document that the persistence action was executed on.
This enables CouchbaseOrm to support large hierarchies and to handle optimized
atomic updates efficiently (without invoking callbacks throughout the document
hierarchy).

Note that using callbacks for domain logic is a bad design practice, and can
lead to unexpected errors that are hard to debug when callbacks in
the chain halt execution. It is our recommendation to only use them
for cross-cutting concerns, like queueing up background jobs.

.. code-block:: ruby

   class Article < CouchabseOrm::Base
     attribute :name, type: String
     attribute :body, type: String
     attribute :slug, type: String

     before_create :send_message

     after_save do |document|
       # Handle callback here.
     end

     protected
     def send_message
       # Message sending code here.
     end
   end

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

.. code-block:: ruby

   class Article < CouchabseOrm::Base
     attribute :name, type: String

     set_callback(:create, :before) do |document|
       # Message sending code here.
     end
   end