ruby on rails - What is the order of ActiveRecord callbacks and validations?

Question

I was wondering in what order are callbacks and validations called when an ActiveRecord object is created.

Let’s say I have some custom validations & callbacks like the following:

validates :reference_code, :if => :reference_code, :on => :create
before_create :assign_reference

which one will run first? The callback needs to happen first or else the validation may fail.

Answer 1

The most-up-to-date version of this list for the latest version of Rails can be found in the ActiveRecord::Callbacks documentation. The lists for Rails 4, 3 & 2 are below.

Rails 4

The most up-to-date version of this list can be found in the Rails 4 Guides.

Creating an object

• before_validation
• after_validation
• before_save
• around_save
• before_create
• around_create
• after_create
• after_save
• after_commit/after_rollback

Updating an object

• before_validation
• after_validation
• before_save
• around_save
• before_update
• around_update
• after_update
• after_save
• after_commit/after_rollback

Destroying an object

• before_destroy
• around_destroy
• after_destroy
• after_commit/after_rollback

Rails 3

The most up-to-date version of this list can be found in the Rails 3 Guides.

Creating an object

• before_validation
• after_validation
• before_save
• around_save
• before_create
• around_create
• after_create
• after_save

Updating an object

• before_validation
• after_validation
• before_save
• around_save
• before_update
• around_update
• after_update
• after_save

Destroying an object

• before_destroy
• around_destroy
• after_destroy

Rails 2

The most up-to-date version of this list can be found in the Rails 2.3 Guides

Creating an object

• before_validation
• before_validation_on_create
• after_validation
• after_validation_on_create
• before_save
• before_create
• INSERT operation
• after_create
• after_save

Updating an object

• before_validation
• before_validation_on_update
• after_validation
• after_validation_on_update
• before_save
• before_update
• UPDATE operation
• after_update
• after_save

Destroying an object

• before_destroy
• DELETE operation
• after_destroy

Since you need to first validate the reference_code, the assign_reference method can be called in the after_validation callback or any callback appearing after it in the list I provided above.