Skill: Events and behaviors

Read the bundled conventions before applying this skill.

Decisions that affect behavior

• Distinguish component instance events, class-level handlers, and behavior-owned handlers. Preserve registration scope/order and detach the matching handler when required. Class handlers and global application state can outlive a single test or request in a worker; avoid accidental repeated registration.
• Component behavior definitions attach lazily; a behavior name identifies its attachment, and replacing a named behavior can detach prior hooks. Preserve inherited behaviors and intended order instead of returning a fresh unrelated configuration from an override.
• Event::$handled stops remaining handlers; cancelable event validity is a separate contract. Inspect the event class and triggering method before assuming returning false from an arbitrary callback cancels the underlying operation.
• Lifecycle behaviors depend on their event being triggered. Bulk/direct database updates may bypass ActiveRecord events, so Timestamp/Blameable/typecast/locking behavior is not guaranteed on every SQL write. Preserve trusted ownership values and avoid assuming a web user exists in console execution.
• AttributeTypecastBehavior’s configured timing matters: afterValidate, beforeSave, afterSave, and afterFind are separate decisions. Type conversion is not input validation. Test the actual value at the intended lifecycle boundary.
• An after-event is not inherently an after-commit event. Do not send external mail or invalidate irreversible external state based solely on a database event if the surrounding transaction can still fail. Preserve the application’s existing transaction and side-effect arrangement.

Observable acceptance

Exercise the real triggering operation and assert handler order, count, mutation, and cancellation according to the relevant event contract. For behaviors verify attachment/replacement/detachment and inherited behavior preservation where changed. For record behaviors compare expected values after normal persistence and any explicit bypass path touched by the task. Restore global handlers between tests.

Evidence routes

Read framework/base/{Component,Event,Behavior,ModelEvent,ActionEvent}.php, framework/db/BaseActiveRecord.php, and the affected file in framework/behaviors/. Tests: tests/framework/base/{ComponentTest,EventTest,BehaviorTest}.php and tests/framework/behaviors/{AttributeTypecastBehaviorTest,TimestampBehaviorTest,BlameableBehaviorConsoleTest,OptimisticLockBehaviorTest}.php. Guides: concept-events, concept-behaviors.

Install and activate this skill

Select yii2-events-behaviors in the installation and client verification guide. Install the complete bundle, including referenced resources. The canonical SKILL.md is also available for direct reading.

Continue with the related framework guide.