All helper methods take the following arguments:
- __PACKAGE__>method_name('relname', 'Foreign::Class', $cond, $attrs);
+ __PACKAGE__>$method_name('relname', 'Foreign::Class', $cond, $attrs);
Both C<$cond> and C<$attrs> are optional. Pass C<undef> for C<$cond> if
you want to use the default value for it, but still want to set C<$attrs>.
-The following attributes are recognize:
-
-=head2 join_type
-
-Explicitly specifies the type of join to use in the relationship. Any SQL
-join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in the SQL
-command immediately before C<JOIN>.
-
-=head2 proxy
-
-An arrayref containing a list of accessors in the foreign class to proxy in
-the main class. If, for example, you do the following:
-
- __PACKAGE__->might_have(bar => 'Bar', undef, { proxy => qw[/ margle /] });
-
-Then, assuming Bar has an accessor named margle, you can do:
-
- my $obj = Foo->find(1);
- $obj->margle(10); # set margle; Bar object is created if it doesn't exist
+See L<DBIx::Class::Relationship::Base> for a list of valid attributes.
=head2 belongs_to
- my $f_obj = $obj->relname;
+ # in a Bar class (where Foo has many Bars)
+ __PACKAGE__->belongs_to(foo => Foo);
+ my $f_obj = $obj->foo;
+ $obj->foo($new_f_obj);
- $obj->relname($new_f_obj);
+Creates a relationship where the calling class stores the foreign class's
+primary key in one (or more) of its columns. If $cond is a column name
+instead of a join condition hash, that is used as the name of the column
+holding the foreign key. If $cond is not given, the relname is used as
+the column name.
-Creates a relationship where we store the foreign class' PK; if $join is a
-column name instead of a condition that is assumed to be the FK, if not
-has_many assumes the FK is the relname is that is a column on the current
-class.
+NOTE: If you are used to L<Class::DBI> relationships, this is the equivalent
+of C<has_a>.
=head2 has_many
- my @f_obj = $obj->relname($cond?, $attrs?);
- my $f_result_set = $obj->relname($cond?, $attrs?);
+ # in a Foo class (where Foo has many Bars)
+ __PACKAGE__->has_many(bar => Bar, 'foo');
+ my $f_resultset = $obj->foo;
+ my $f_resultset = $obj->foo({ name => { LIKE => '%macaroni%' }, { prefetch => [qw/bar/] });
+ my @f_obj = $obj->foo;
- $obj->add_to_relname(\%col_data);
+ $obj->add_to_foo(\%col_data);
-Creates a one-many relationship with another class;
+Creates a one-to-many relationship, where the corresponding elements of the
+foreign class store the calling class's primary key in one (or more) of its
+columns. You should pass the name of the column in the foreign class as the
+$cond argument, or specify a complete join condition.
+
+If you delete an object in a class with a C<has_many> relationship, all
+related objects will be deleted as well. However, any database-level
+cascade or restrict will take precedence.
=head2 might_have
- my $f_obj = $obj->relname;
+ __PACKAGE__->might_have(baz => Baz);
+ my $f_obj = $obj->baz; # to get the baz object
+
+Creates an optional one-to-one relationship with a class, where the foreign class
+stores our primary key in one of its columns. Defaults to the primary key of the
+foreign class unless $cond specifies a column or join condition.
-Creates an optional one-one relationship with another class; defaults to PK-PK
-for the join condition unless a condition is specified.
+If you update or delete an object in a class with a C<might_have> relationship,
+the related object will be updated or deleted as well. Any database-level update
+or delete constraints will override this behavior.
=head2 has_one
- my $f_obj = $obj->relname;
+ __PACKAGE__->has_one(gorch => Gorch);
+ my $f_obj = $obj->gorch;
-Creates a one-one relationship with another class; defaults to PK-PK for
-the join condition unless a condition is specified.
+Creates a one-to-one relationship with another class. This is just like C<might_have>,
+except the implication is that the other object is always present. The only different
+between C<has_one> and C<might_have> is that C<has_one> uses an (ordinary) inner join,
+whereas C<might_have> uses a left join.
=cut
__PACKAGE__->add_relationship('relname', 'Foreign::Class', $cond, $attrs);
The condition needs to be an SQL::Abstract-style representation of the
-join between the tables - for example if you're creating a rel from Foo to Bar
+join between the tables. For example, if you're creating a rel from Foo to Bar,
{ 'foreign.foo_id' => 'self.id' }
-will result in a JOIN clause like
+will result in the JOIN clause
foo me JOIN bar bar ON bar.foo_id = me.id
+You can specify as many foreign => self mappings as necessary.
+
+Valid attributes are as follows:
+
+=over 4
+
+=item join_type
+
+Explicitly specifies the type of join to use in the relationship. Any SQL
+join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in the SQL
+command immediately before C<JOIN>.
+
+=item proxy
+
+An arrayref containing a list of accessors in the foreign class to proxy in
+the main class. If, for example, you do the following:
+
+ __PACKAGE__->might_have(bar => 'Bar', undef, { proxy => qw[/ margle /] });
+
+Then, assuming Bar has an accessor named margle, you can do:
+
+ my $obj = Foo->find(1);
+ $obj->margle(10); # set margle; Bar object is created if it doesn't exist
+
+=item accessor
+
+Specifies the type of accessor that should be created for the relationship.
+Valid values are C<single> (for when there is only a single related object),
+C<multi> (when there can be many), and C<filter> (for when there is a single
+related object, but you also want the relationship accessor to double as
+a column accessor). For C<multi> accessors, an add_to_* method is also
+created, which calls C<create_related> for the relationship.
+
+=back
+
=cut
sub add_relationship {
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