NAME

DBIx::Class::DeleteAction - Define delete triggers

SYNOPSIS

# Actor DBIC class
package Your::Schema::Actor;
use strict;
use warnings;

use base 'DBIx::Class';

__PACKAGE__->load_components("DeleteAction","PK","Core");

__PACKAGE__->table("actor");
__PACKAGE__->add_columns(qw/name/);

__PACKAGE__->has_many(
   'actorroles' => 'MyDB::Schema::ActorRole',
   { 'foreign.actor' => 'self.id' },
   { delete_action => 'delete' }
);

# Actor Role DBIC class
package Your::Schema::ActorRole;
use strict;
use warnings;

use base 'DBIx::Class';

__PACKAGE__->load_components("DeleteAction","PK","Core");

__PACKAGE__->table("actor_role");
__PACKAGE__->add_columns(qw/name actor production/);

__PACKAGE__->belongs_to(
   'actor' => 'MyDB::Schema::Actor',
   { 'foreign.id' => 'self.actor' },
   { delete_action => sub {
       # Do something special
   } }
);

__PACKAGE__->belongs_to(
   'production' => 'MyDB::Schema::Production',
   { 'foreign.id' => 'self.production' },
   { delete_action => 'deny' }
);

# Somewhere else
$schema->txn_do(sub {
   $actor->delete();    
});
# Deletes all related actorroles only if they don't have a production
# Finally deletes the actor itself

$schema->txn_do(sub {
   $actor_role->delete();    
});
# Calls custom subroutine on actor
# Denies deletion if a production is related

DESCRIPTION

With this DBIx::Class component you can specify actions that should be triggered on a row delete. A delete action is specified by adding the 'delete_action' key to the optional attribute HASH reference when specifing a new relation (see DBIx::Class::Relationship).

The following hash values are supported:

• null

  Set all columns in related rows pointing to this record to NULL. Only works on 'has_many' relationships.

• delete OR cascade

  Delete all related records.

• deny

  Deny deletion if this record is being referenced from other rows.

• CODE reference

  Executes the code referece on delete. The current DBIx::Class::Row object and the name of the relation are passed to the code reference.

• STRING

  Execute a method with the given name. The method will be called on the current DBIx::Class::Row object and will be passed the name of the relation.

• ignore

  Do nothing

Custom delete handlers

If you set the delete_action to execute a method or a code reference the method will be called with the following parameters:

• $self

  The DBIx::Class::Row object the delete action has been called upon.

• Relationship name

  The name of the relationship that is currently being processed.

• Related object(s)

  The related object(s) for the given object and relationship.

  Depending on the type of the relationship this can either be a DBIx::Class::Row or a DBIx::Class::ResultSet object.

• Seen object(s)

  An arraryref with object identifiers which have already been processed. If you want to call another delete method from your code you MUST pass on this variable so that we can ensure that each object/row is handled only once.

  The helper method _delete_action_identifier returns the identification string fot the given object.

• Extra values

  An array of optional extra values that have been passed to delete

delete

$object->delete();
OR
$object->delete($seen_arrayref);
OR
$object->delete($seen_arrayref,@extra_values);

This method overdrives the DBIx::Class::Row delete method.

Make sure that you ALWAYS call delete always from within a TRANSACTION block.

CAVEATS

Note that the delete method in DBIx::Class::ResultSet will not run DeleteAction triggers. See delete_all if you need triggers to run.

Any database-level cascade, restrict or trigger will be performed AFTER a DBIx-Class-DeleteAction based trigger.

Always use transactions, or else you might end up with inconsistent data.

SUPPORT

Please report any bugs or feature requests to bug-dbix-class-deleteaction@rt.cpan.org, or through the web interface at http://rt.cpan.org/Public/Bug/Report.html?Queue=DBIx::Class::DeleteAction. I will be notified, and then you'll automatically be notified of progress on your report as I make changes.

AUTHOR

Maroš Kollár
CPAN ID: MAROS
maros [at] k-1.com
L<http://www.revdev.at>

ACKNOWLEDGEMENTS

This module was written for Revdev http://www.revdev.at, a nice litte software company I run with Koki and Domm (http://search.cpan.org/~domm/).

COPYRIGHT

DBIx::Class::DeleteAction is Copyright (c) 2008 Maroš Kollár - http://www.revdev.at

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.