Docs are available here
Looks like the following options are supported:
-
nil– do nothing (default). -
:destroy– causes all the associated objects to also be destroyed. -
:delete_all– causes all the associated objects to be deleted directly from the database (so callbacks will not be executed). -
:nullify– causes the foreign keys to be set to NULL. Callbacks are not executed. -
:restrict_with_exception– causes an exception to be raised if there are any associated records. -
:restrict_with_error– causes an error to be added to the owner if there are any associated objects.