my $fredsbooks = $schema->resultset('Author')->find({ Name => 'Fred' })->books;
Each relationship sets up an accessor method on the
-L<DBIx::Class::Manual::Glossary/"Row"> objects that represent the items
-of your table. From L<DBIx::Class::Manual::Glossary/"ResultSet"> objects,
+L<Result|DBIx::Class::Manual::Glossary/"Result"> objects that represent the items
+of your table. From L<ResultSet|DBIx::Class::Manual::Glossary/"ResultSet"> objects,
the relationships can be searched using the "search_related" method.
-In list context, each returns a list of Row objects for the related class,
+In list context, each returns a list of Result objects for the related class,
in scalar context, a new ResultSet representing the joined tables is
returned. Thus, the calls can be chained to produce complex queries.
Since the database is not actually queried until you attempt to retrieve
=item accessor_name
This argument is the name of the method you can call on a
-L<DBIx::Class::Row> object to retrieve the instance of the foreign
+L<Result|DBIx::Class::Manual::ResultClass> object to retrieve the instance of the foreign
class matching this relationship. This is often called the
C<relation(ship) name>.
=item cond
A hashref, arrayref or coderef specifying a custom join expression. For
-more info see L<DBIx::Class::Relationship/condition>.
+more info see L<DBIx::Class::Relationship::Base/condition>.
=back
# in a Book class (where Author has many Books)
- My::DBIC::Schema::Book->belongs_to(
- author =>
- 'My::DBIC::Schema::Author',
+ My::DBIC::Schema::Book->belongs_to(
+ author =>
+ 'My::DBIC::Schema::Author',
'author_id'
);
My::DBIC::Schema::Book->belongs_to(
author =>
'My::DBIC::Schema::Author',
- { 'foreign.author_id' => 'self.author_id' }
+ { 'foreign.author_id' => 'self.author_id' }
);
# OR (similar result but uglier accessor name)
- My::DBIC::Schema::Book->belongs_to(
+ My::DBIC::Schema::Book->belongs_to(
author_id =>
'My::DBIC::Schema::Author'
);
# To retrieve the plain id if you used the ugly version:
$book->get_column('author_id');
-
-If the relationship is optional -- i.e. the column containing the
-foreign key can be NULL -- then the belongs_to relationship does the
-right thing. Thus, in the example above C<< $obj->author >> would
-return C<undef>. However in this case you would probably want to set
-the L<join_type|DBIx::Class::Relationship/join_type> attribute so that
-a C<LEFT JOIN> is done, which makes complex resultsets involving
-C<join> or C<prefetch> operations work correctly. The modified
-declaration is shown below:
+If some of the foreign key columns are
+L<nullable|DBIx::Class::ResultSource/is_nullable> you probably want to set
+the L<join_type|DBIx::Class::Relationship::Base/join_type> attribute to
+C<left> explicitly so that SQL expressing this relation is composed with
+a C<LEFT JOIN> (as opposed to C<INNER JOIN> which is default for
+L</belongs_to> relationships). This ensures that relationship traversal
+works consistently in all situations. (i.e. resultsets involving
+L<join|DBIx::Class::ResultSet/join> or
+L<prefetch|DBIx::Class::ResultSet/prefetch>).
+The modified declaration is shown below:
# in a Book class (where Author has_many Books)
__PACKAGE__->belongs_to(
- author =>
+ author =>
'My::DBIC::Schema::Author',
- 'author',
+ 'author',
{ join_type => 'left' }
);
-
Cascading deletes are off by default on a C<belongs_to>
relationship. To turn them on, pass C<< cascade_delete => 1 >>
in the $attr hashref.
=over 4
-=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs?
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, L<\%attrs?|DBIx::Class::ResultSet/ATTRIBUTES>
=back
Creates a one-to-many relationship where the foreign class refers to
this class's primary key. This relationship refers to zero or more
-records in the foreign table (e.g. a C<LEFT JOIN>). This relationship
+records in the foreign table (e.g. a C<LEFT JOIN>). This relationship
defaults to using the end of this classes namespace as the foreign key
in C<$related_class> to resolve the join, unless C<$their_fk_column>
specifies the foreign key column in C<$related_class> or C<cond>
=item accessor_name
This argument is the name of the method you can call on a
-L<DBIx::Class::Row> object to retrieve a resultset of the related
-class restricted to the ones related to the row object. In list
-context it returns the row objects. This is often called the
+L<Result|DBIx::Class::Manual::ResultClass> object to retrieve a resultset of the related
+class restricted to the ones related to the result object. In list
+context it returns the result objects. This is often called the
C<relation(ship) name>.
Use this accessor_name in L<DBIx::Class::ResultSet/join>
=item cond
A hashref, arrayref or coderef specifying a custom join expression. For
-more info see L<DBIx::Class::Relationship/condition>.
+more info see L<DBIx::Class::Relationship::Base/condition>.
=back
# in an Author class (where Author has_many Books)
# assuming related class is storing our PK in "author_id"
My::DBIC::Schema::Author->has_many(
- books =>
- 'My::DBIC::Schema::Book',
+ books =>
+ 'My::DBIC::Schema::Book',
'author_id'
);
# OR (same result)
My::DBIC::Schema::Author->has_many(
- books =>
- 'My::DBIC::Schema::Book',
+ books =>
+ 'My::DBIC::Schema::Book',
{ 'foreign.author_id' => 'self.id' },
);
# OR (similar result, assuming related_class is storing our PK, in "author")
# (the "author" is guessed at from "Author" in the class namespace)
My::DBIC::Schema::Author->has_many(
- books =>
- 'My::DBIC::Schema::Book',
+ books =>
+ 'My::DBIC::Schema::Book',
);
# Usage
- # resultset of Books belonging to author
+ # resultset of Books belonging to author
my $booklist = $author->books;
# resultset of Books belonging to author, restricted by author name
=over 4
-=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs?
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, L<\%attrs?|DBIx::Class::ResultSet/ATTRIBUTES>
=back
=item accessor_name
This argument is the name of the method you can call on a
-L<DBIx::Class::Row> object to retrieve the instance of the foreign
+L<Result|DBIx::Class::Manual::ResultClass> object to retrieve the instance of the foreign
class matching this relationship. This is often called the
C<relation(ship) name>.
=item cond
A hashref, arrayref or coderef specifying a custom join expression. For
-more info see L<DBIx::Class::Relationship/condition>.
+more info see L<DBIx::Class::Relationship::Base/condition>.
=back
=over 4
-=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, \%attrs?
+=item Arguments: $accessor_name, $related_class, $their_fk_column|\%cond|\@cond|\&cond?, L<\%attrs?|DBIx::Class::ResultSet/ATTRIBUTES>
=back
=item accessor_name
This argument is the name of the method you can call on a
-L<DBIx::Class::Row> object to retrieve the instance of the foreign
+L<Result|DBIx::Class::Manual::ResultClass> object to retrieve the instance of the foreign
class matching this relationship. This is often called the
C<relation(ship) name>.
=item cond
A hashref, arrayref or coderef specifying a custom join expression. For
-more info see L<DBIx::Class::Relationship/condition>.
+more info see L<DBIx::Class::Relationship::Base/condition>.
=back
# Every book has exactly one ISBN
My::DBIC::Schema::Book->has_one(
- isbn =>
+ isbn =>
'My::DBIC::Schema::ISBN',
'book_id',
);
# OR (same result, assuming related_class stores our PK)
My::DBIC::Schema::Book->has_one(
- isbn =>
+ isbn =>
'My::DBIC::Schema::ISBN',
);
# OR (same result)
My::DBIC::Schema::Book->has_one(
- isbn =>
+ isbn =>
'My::DBIC::Schema::ISBN',
{ 'foreign.book_id' => 'self.id' },
);
=over 4
-=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, \%attrs?
+=item Arguments: $accessor_name, $link_rel_name, $foreign_rel_name, L<\%attrs?|DBIx::Class::ResultSet/ATTRIBUTES>
=back
C<many_to_many> is not strictly a relationship in its own right. Instead, it is
a bridge between two resultsets which provide the same kind of convenience
-accessors as true relationships provide. Although the accessor will return a
-resultset or collection of objects just like has_many does, you cannot call
+accessors as true relationships provide. Although the accessor will return a
+resultset or collection of objects just like has_many does, you cannot call
C<related_resultset> and similar methods which operate on true relationships.
=over
=item accessor_name
This argument is the name of the method you can call on a
-L<DBIx::Class::Row> object to retrieve the rows matching this
+L<Result|DBIx::Class::Manual::ResultClass> object to retrieve the rows matching this
relationship.
On a many_to_many, unlike other relationships, this cannot be used in
1;
-=head1 AUTHORS
+=head1 AUTHOR AND CONTRIBUTORS
-see L<DBIx::Class>
+See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class
=head1 LICENSE