frappe-syntax-hooks-events

Frappe doc_events let you register handler functions for specific lifecycle events like on_submit and on_cancel. You map event names to handler paths in hooks to ensure custom logic executes safely when documents transition states.

Frappe document lifecycle hooks fire in a specific sequence: validate runs before before_save, and on_submit fires after the document is submitted. Mastering this event order prevents silent failures and incorrect assumptions in custom validation logic.

To extend existing DocTypes across multiple apps, use extend_doctype_class or override_doctype_class in your hooks. This allows your app to modify another app's behavior without causing silent failures or broken overrides during updates.

Yes, Frappe doc_events configuration supports wildcard hooks to register handlers for all DocTypes. This targets document changes globally, applying logic like audit logging to every document without specifying each DocType individually.

Frappe document hooks fail silently during update-after-submit scenarios if you use incorrect event names or mismatched handler signatures. Placing logic in the right hook with safe frappe.throw calls prevents these silent failures.

Use override_doctype_class to completely replace a DocType's class behavior, whereas extend_doctype_class adds to existing methods safely. Choosing the right approach ensures safe extensibility when modifying another app's document lifecycle.