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Diffstat (limited to 'guides/source/active_record_callbacks.md')
-rw-r--r-- | guides/source/active_record_callbacks.md | 63 |
1 files changed, 54 insertions, 9 deletions
diff --git a/guides/source/active_record_callbacks.md b/guides/source/active_record_callbacks.md index 77bd3c97e8..5946acb412 100644 --- a/guides/source/active_record_callbacks.md +++ b/guides/source/active_record_callbacks.md @@ -1,4 +1,4 @@ -**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.** +**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON https://guides.rubyonrails.org.** Active Record Callbacks ======================= @@ -117,6 +117,10 @@ Here is a list with all the available Active Record callbacks, listed in the sam WARNING. `after_save` runs both on create and update, but always _after_ the more specific callbacks `after_create` and `after_update`, no matter the order in which the macro calls were executed. +NOTE: `before_destroy` callbacks should be placed before `dependent: :destroy` +associations (or use the `prepend: true` option), to ensure they execute before +the records are deleted by `dependent: :destroy`. + ### `after_initialize` and `after_find` The `after_initialize` callback will be called whenever an Active Record object is instantiated, either by directly using `new` or when a record is loaded from the database. It can be useful to avoid the need to directly override your Active Record `initialize` method. @@ -180,9 +184,9 @@ class Company < ApplicationRecord after_touch :log_when_employees_or_company_touched private - def log_when_employees_or_company_touched - puts 'Employee/Company was touched' - end + def log_when_employees_or_company_touched + puts 'Employee/Company was touched' + end end >> @employee = Employee.last @@ -190,8 +194,8 @@ end # triggers @employee.company.touch >> @employee.touch -Employee/Company was touched An Employee was touched +Employee/Company was touched => true ``` @@ -209,6 +213,7 @@ The following methods trigger callbacks: * `save!` * `save(validate: false)` * `toggle!` +* `touch` * `update_attribute` * `update` * `update!` @@ -241,7 +246,6 @@ Just as with validations, it is also possible to skip callbacks by using the fol * `increment` * `increment_counter` * `toggle` -* `touch` * `update_column` * `update_columns` * `update_all` @@ -254,9 +258,13 @@ Halting Execution As you start registering new callbacks for your models, they will be queued for execution. This queue will include all your model's validations, the registered callbacks, and the database operation to be executed. -The whole callback chain is wrapped in a transaction. If any _before_ callback method returns exactly `false` or raises an exception, the execution chain gets halted and a ROLLBACK is issued; _after_ callbacks can only accomplish that by raising an exception. +The whole callback chain is wrapped in a transaction. If any callback raises an exception, the execution chain gets halted and a ROLLBACK is issued. To intentionally stop a chain use: -WARNING. Any exception that is not `ActiveRecord::Rollback` or `ActiveRecord::RecordInvalid` will be re-raised by Rails after the callback chain is halted. Raising an exception other than `ActiveRecord::Rollback` or `ActiveRecord::RecordInvalid` may break code that does not expect methods like `save` and `update_attributes` (which normally try to return `true` or `false`) to raise an exception. +```ruby +throw :abort +``` + +WARNING. Any exception that is not `ActiveRecord::Rollback` or `ActiveRecord::RecordInvalid` will be re-raised by Rails after the callback chain is halted. Raising an exception other than `ActiveRecord::Rollback` or `ActiveRecord::RecordInvalid` may break code that does not expect methods like `save` and `update` (which normally try to return `true` or `false`) to raise an exception. Relational Callbacks -------------------- @@ -311,6 +319,14 @@ class Order < ApplicationRecord end ``` +As the proc is evaluated in the context of the object, it is also possible to write this as: + +```ruby +class Order < ApplicationRecord + before_save :normalize_card_number, if: Proc.new { paid_with_card? } +end +``` + ### Multiple Conditions for Callbacks When writing conditional callbacks, it is possible to mix both `:if` and `:unless` in the same callback declaration: @@ -400,7 +416,7 @@ end NOTE: The `:on` option specifies when a callback will be fired. If you don't supply the `:on` option the callback will fire for every action. -Since using `after_commit` callback only on create, update or delete is +Since using `after_commit` callback only on create, update, or delete is common, there are aliases for those operations: * `after_create_commit` @@ -420,3 +436,32 @@ end ``` WARNING. The `after_commit` and `after_rollback` callbacks are called for all models created, updated, or destroyed within a transaction block. However, if an exception is raised within one of these callbacks, the exception will bubble up and any remaining `after_commit` or `after_rollback` methods will _not_ be executed. As such, if your callback code could raise an exception, you'll need to rescue it and handle it within the callback in order to allow other callbacks to run. + +WARNING. Using both `after_create_commit` and `after_update_commit` in the same model will only allow the last callback defined to take effect, and will override all others. + +```ruby +class User < ApplicationRecord + after_create_commit :log_user_saved_to_db + after_update_commit :log_user_saved_to_db + + private + def log_user_saved_to_db + puts 'User was saved to database' + end +end + +# prints nothing +>> @user = User.create + +# updating @user +>> @user.save +=> User was saved to database +``` + +To register callbacks for both create and update actions, use `after_commit` instead. + +```ruby +class User < ApplicationRecord + after_commit :log_user_saved_to_db, on: [:create, :update] +end +``` |