[Dbix-class] DBIx::Class::Schema::Loader and on_delete/cascade_delete

[Andy Lester]

(Also posted to http://perlmonks.org/?node_id=954009)

I'm using 0.07017 of DBIx::Class::Schema::Loader, and I'm confused by its output for two tables with a FK relationship.

Here are excerpts of two related tables, List and Notification. Notification is a subtable of List, with a proper FK in the (Postgres) database, and it's defined as ON DELETE CASCADE in the DB. These snippets were from the files generated by ::Loader.


# from TT/Schema/List.pm

__PACKAGE__->has_many(
  "notification",
  "TT::Schema::Notification",
  { "foreign.listid" => "self.listid", "foreign.ltype" => "self.ltype"
 },
  { cascade_copy => 0, cascade_delete => 0 },
);

# from TT/Schema/Notification.pm

__PACKAGE__->belongs_to(
  "list",
  "TT::Schema::List",
  { listid => "listid", ltype => "ltype" },
  { is_deferrable => 1, on_delete => "CASCADE", on_update => "CASCADE"
 },
);

The DBIx::Class docs say

"By default, DBIx::Class cascades deletes across has_many, has_one and might_have relationships. You can disable this behaviour on a per-relationship basis by supplying cascade_delete => 0 in the relationship attributes. The cascaded operations are performed after the requested delete, so if your database has a constraint on the relationship, it will have deleted/updated the related records or raised an exception before DBIx::Class gets to perform the cascaded operation."

which I take to mean that cascade_delete should be false if the database is going to take care of the deleting for us. In this case, it will, because there's a foreign key from notification up to list with ON DELETE CASCADE. But then why is on_delete=>'CASCADE'?

It seems to me that the cascade_delete in the List.pm should be set to 1, to match the on_delete => 'CASCADE' in the Notification.pm. Or, that they should be 0 and undef, respectively. But I would think they should match.

Am I misunderstanding something? Or is DBIx::Class::Schema::Loader not building my schema correctly?

Thanks,
xoxo,
Andy

--
Andy Lester => andy at petdance.com => www.petdance.com => AIM:petdance