Class::DBI::RelationshUser)Contributed Perl DocumenClass::DBI::Relationship(3)NAMEClass::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 v5.14.1 2005-09-16 Class::DBI::Relationship(3)
