1 package DBIx::Class::Relationship;
6 use base qw/DBIx::Class/;
8 __PACKAGE__->load_own_components(qw/
18 DBIx::Class::Relationship - Inter-table relationships
24 This class handles relationships between the tables in your database
25 model. It allows you to set up relationships and perform joins on them.
27 Only the helper methods for setting up standard relationship types
28 are documented here. For the basic, lower-level methods, see
29 L<DBIx::Class::Relationship::Base>.
33 All helper methods take the following arguments:
35 __PACKAGE__>$method_name('relname', 'Foreign::Class', $cond, $attrs);
37 Both C<$cond> and C<$attrs> are optional. Pass C<undef> for C<$cond> if
38 you want to use the default value for it, but still want to set C<$attrs>.
39 See L<DBIx::Class::Relationship::Base> for a list of valid attributes.
43 # in a Bar class (where Foo has many Bars)
44 __PACKAGE__->belongs_to(foo => Foo);
45 my $f_obj = $obj->foo;
46 $obj->foo($new_f_obj);
48 Creates a relationship where the calling class stores the foreign class's
49 primary key in one (or more) of its columns. If $cond is a column name
50 instead of a join condition hash, that is used as the name of the column
51 holding the foreign key. If $cond is not given, the relname is used as
54 NOTE: If you are used to L<Class::DBI> relationships, this is the equivalent
59 # in a Foo class (where Foo has many Bars)
60 __PACKAGE__->has_many(bar => Bar, 'foo');
61 my $f_resultset = $obj->foo;
62 my $f_resultset = $obj->foo({ name => { LIKE => '%macaroni%' }, { prefetch => [qw/bar/] });
63 my @f_obj = $obj->foo;
65 $obj->add_to_foo(\%col_data);
67 Creates a one-to-many relationship, where the corresponding elements of the
68 foreign class store the calling class's primary key in one (or more) of its
69 columns. You should pass the name of the column in the foreign class as the
70 $cond argument, or specify a complete join condition.
72 If you delete an object in a class with a C<has_many> relationship, all
73 related objects will be deleted as well. However, any database-level
74 cascade or restrict will take precedence.
78 __PACKAGE__->might_have(baz => Baz);
79 my $f_obj = $obj->baz; # to get the baz object
81 Creates an optional one-to-one relationship with a class, where the foreign class
82 stores our primary key in one of its columns. Defaults to the primary key of the
83 foreign class unless $cond specifies a column or join condition.
85 If you update or delete an object in a class with a C<might_have> relationship,
86 the related object will be updated or deleted as well. Any database-level update
87 or delete constraints will override this behavior.
91 __PACKAGE__->has_one(gorch => Gorch);
92 my $f_obj = $obj->gorch;
94 Creates a one-to-one relationship with another class. This is just like C<might_have>,
95 except the implication is that the other object is always present. The only different
96 between C<has_one> and C<might_have> is that C<has_one> uses an (ordinary) inner join,
97 whereas C<might_have> uses a left join.
102 __PACKAGE__->many_to_many( 'accessorname' => 'a_to_b', 'table_b' );
103 my @f_objs = $obj_a->accessorname;
111 Matt S. Trout <mst@shadowcatsystems.co.uk>
115 You may distribute this code under the same terms as Perl itself.