ActiveRecord callbacks execute sequence

before_validation
before_validation_on_create
after_validation
after_validation_on_create
before_save
before_create
insert operation
after_create
after_save

ActiveRecord callback instance methods execute ways on create will revok before_validation_on_create callback before ActiveRecord validation methods, and before_create callback will revoke after ActiveRecord validation methods and helpers, like validates_associated, validates_each.
If a new record has some error, and will not be validated by ActiveRecord validation methods and helpers, then after_validation and before_create callback will not be revoked.