class::dbi::cascade::none(3pm) [debian man page]

Class::DBI::Cascade::None(3pm)				User Contributed Perl Documentation			    Class::DBI::Cascade::None(3pm)

NAME

       Class::DBI::Cascade::None - Do nothing upon deletion

DESCRIPTION

       This is a Cascading Delete strategy that will do nothing, leaving orphaned records behind.

       It is the base class for most ofther Cascade strategies, and so provides several important methods:

CONSTRUCTOR

   new
	       my $strategy = Cascade::Class->new($Relationship);

       This must be instantiated with a Class::DBI::Relationship object.

METHODS

   foreign_for
	       my $iterator = $strategy->foreign_for($obj);

       This will return all the objects which are foreign to $obj across the relationship. It's a normal Class::DBI search you can get the results
       either as a list or as an iterator.

   cascade
	       $strategy->cascade($obj);

       Cascade across the related objects to $obj.

WRITING NEW STRATEGIES

       Creating a Cascade strategy should be fairly simple. You usually just need to inherit from here, and then supply a cascade() method that
       does the required thing with the results from foreign_for().

       So, for example, Cascade::Delete is implemented simply as:

	       package Class::DBI::Cascade::Delete;

	       use base 'Class::DBI::Cascade::None';

	       sub cascade {
		       my ($self, $obj) = @_;
		       $self->foreign_for($obj)->delete_all;
	       }

perl v5.12.4							    2005-09-14					    Class::DBI::Cascade::None(3pm)

Class::DBI::Relationship(3pm)				User Contributed Perl Documentation			     Class::DBI::Relationship(3pm)

NAME

       Class::DBI::Relationship - base class for Relationships

DESCRIPTION

       A Class::DBI class represents a database table. But merely being able to represent single tables isn't really that useful - databases are
       all about relationships.

       So, Class::DBI provides a variety of Relationship models to represent common database occurences (HasA, HasMany and MightHave), and
       provides a way to add others.

SUBCLASSING

       Relationships should inherit from Class::DBI::Relationship, and provide a variety of methods to represent the relationship. For examples of
       how these are used see Class::DBI::Relationship::HasA, Class::DBI::Relationship::HasMany and Class::DBI::Relationship::MightHave.

   remap_arguments
	       sub remap_arguments {
		       my $self = shift;
		       # process @_;
		       return ($class, accessor, $foreign_class, $args)
	       }

       Subclasses should define a 'remap_arguments' method that takes the arguments with which your relationship method will be called, and
       transforms them into the structure that the Relationship modules requires.  If this method is not provided, then it is assumed that your
       method will be called with these 3 arguments in this order.

       This should return a list of 4 items:

       class
	   The Class::DBI subclass to which this relationship applies. This will be passed in to you from the caller who actually set up the
	   relationship, and is available for you to call methods on whilst performing this mapping. You should almost never need to change this.

	   This usually an entire application base class (or Class::DBI itself), but could be a single class wishing to override a default
	   relationship.

       accessor
	   The method in the class which will provide access to the results of the relationship.

       foreign_class
	   The class for the table with which the class has a relationship.

       args
	   Any additional args that your relationship requires.  It is recommended that you use this as a hashref to store any extra information
	   your relationship needs rather than adding extra accessors, as this information will all be stored in the 'meta_info'.

   triggers
	       sub triggers {
		       return (
			       before_create => sub { ... },
			       after_create  => sub { ... },
		       );
	       }

       Subclasses may define a 'triggers' method that returns a list of triggers that the relationship needs. This method can be omitted if there
       are no triggers to be set up.

   methods
	       sub methods {
		       return (
			       method1 => sub { ... },
			       method2 => sub { ... },
		       );
	       }

       Subclasses may define a 'methods' method that returns a list of methods to facilitate the relationship that should be created in the
       calling Class::DBI class.  This method can be omitted if there are no methods to be set up.

perl v5.12.4							    2005-09-16					     Class::DBI::Relationship(3pm)