1 package DBIx::Class::Relationship::Base;
7 use base qw/DBIx::Class/;
11 DBIx::Class::Relationship::Base - Inter-table relationships
17 This class provides methods to describe the relationships between the
18 tables in your database model. These are the "bare bones" relationships
19 methods, for predefined ones, look in L<DBIx::Class::Relationship>.
23 =head2 add_relationship
27 =item Arguments: 'relname', 'Foreign::Class', $cond, $attrs
31 __PACKAGE__->add_relationship('relname', 'Foreign::Class', $cond, $attrs);
33 The condition needs to be an L<SQL::Abstract>-style representation of the
34 join between the tables. When resolving the condition for use in a C<JOIN>,
35 keys using the pseudo-table C<foreign> are resolved to mean "the Table on the
36 other side of the relationship", and values using the pseudo-table C<self>
37 are resolved to mean "the Table this class is representing". Other
38 restrictions, such as by value, sub-select and other tables, may also be
39 used. Please check your database for C<JOIN> parameter support.
41 For example, if you're creating a relationship from C<Author> to C<Book>, where
42 the C<Book> table has a column C<author_id> containing the ID of the C<Author>
45 { 'foreign.author_id' => 'self.id' }
47 will result in the C<JOIN> clause
49 author me JOIN book book ON book.author_id = me.id
51 For multi-column foreign keys, you will need to specify a C<foreign>-to-C<self>
52 mapping for each column in the key. For example, if you're creating a
53 relationship from C<Book> to C<Edition>, where the C<Edition> table refers to a
54 publisher and a type (e.g. "paperback"):
57 'foreign.publisher_id' => 'self.publisher_id',
58 'foreign.type_id' => 'self.type_id',
61 This will result in the C<JOIN> clause:
63 book me JOIN edition edition ON edition.publisher_id = me.publisher_id
64 AND edition.type_id = me.type_id
66 Each key-value pair provided in a hashref will be used as C<AND>ed conditions.
67 To add an C<OR>ed condition, use an arrayref of hashrefs. See the
68 L<SQL::Abstract> documentation for more details.
70 In addition to standard result set attributes, the following attributes are also valid:
76 Explicitly specifies the type of join to use in the relationship. Any SQL
77 join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in the SQL
78 command immediately before C<JOIN>.
82 An arrayref containing a list of accessors in the foreign class to create in
83 the main class. If, for example, you do the following:
85 MyDB::Schema::CD->might_have(liner_notes => 'MyDB::Schema::LinerNotes',
87 proxy => [ qw/notes/ ],
90 Then, assuming MyDB::Schema::LinerNotes has an accessor named notes, you can do:
92 my $cd = MyDB::Schema::CD->find(1);
93 $cd->notes('Notes go here'); # set notes -- LinerNotes object is
94 # created if it doesn't exist
98 Specifies the type of accessor that should be created for the relationship.
99 Valid values are C<single> (for when there is only a single related object),
100 C<multi> (when there can be many), and C<filter> (for when there is a single
101 related object, but you also want the relationship accessor to double as
102 a column accessor). For C<multi> accessors, an add_to_* method is also
103 created, which calls C<create_related> for the relationship.
107 =head2 register_relationship
111 =item Arguments: $relname, $rel_info
115 Registers a relationship on the class. This is called internally by
116 DBIx::Class::ResultSourceProxy to set up Accessors and Proxies.
120 sub register_relationship { }
122 =head2 related_resultset
126 =item Arguments: $relationship_name
128 =item Return Value: $related_resultset
132 $rs = $cd->related_resultset('artist');
134 Returns a L<DBIx::Class::ResultSet> for the relationship named
139 sub related_resultset {
141 $self->throw_exception("Can't call *_related as class methods")
144 my $rel_obj = $self->relationship_info($rel);
145 $self->throw_exception( "No such relationship ${rel}" )
148 return $self->{related_resultsets}{$rel} ||= do {
149 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
150 $attrs = { %{$rel_obj->{attrs} || {}}, %$attrs };
152 $self->throw_exception( "Invalid query: @_" )
153 if (@_ > 1 && (@_ % 2 == 1));
154 my $query = ((@_ > 1) ? {@_} : shift);
156 my $cond = $self->result_source->resolve_condition(
157 $rel_obj->{cond}, $rel, $self
159 if (ref $cond eq 'ARRAY') {
160 $cond = [ map { my $hash;
161 foreach my $key (keys %$_) {
162 my $newkey = $key =~ /\./ ? "me.$key" : $key;
163 $hash->{$newkey} = $_->{$key};
166 foreach my $key (grep { ! /\./ } keys %$cond) {
167 $cond->{"me.$key"} = delete $cond->{$key};
170 $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
171 $self->result_source->related_source($rel)->resultset->search(
177 =head2 search_related
179 @objects = $rs->search_related('relname', $cond, $attrs);
180 $objects_rs = $rs->search_related('relname', $cond, $attrs);
182 Run a search on a related resultset. The search will be restricted to the
183 item or items represented by the L<DBIx::Class::ResultSet> it was called
184 upon. This method can be called on a ResultSet, a Row or a ResultSource class.
189 return shift->related_resultset(shift)->search(@_);
192 =head2 search_related_rs
194 ( $objects_rs ) = $rs->search_related_rs('relname', $cond, $attrs);
196 This method works exactly the same as search_related, except that
197 it garauntees a restultset, even in list context.
201 sub search_related_rs {
202 return shift->related_resultset(shift)->search_rs(@_);
207 $obj->count_related('relname', $cond, $attrs);
209 Returns the count of all the items in the related resultset, restricted by the
210 current item or where conditions. Can be called on a
211 L<DBIx::Class::Manual::Glossary/"ResultSet"> or a
212 L<DBIx::Class::Manual::Glossary/"Row"> object.
218 return $self->search_related(@_)->count;
223 my $new_obj = $obj->new_related('relname', \%col_data);
225 Create a new item of the related foreign class. If called on a
226 L<Row|DBIx::Class::Manual::Glossary/"Row"> object, it will magically
227 set any foreign key columns of the new object to the related primary
228 key columns of the source object for you. The newly created item will
229 not be saved into your storage until you call L<DBIx::Class::Row/insert>
235 my ($self, $rel, $values, $attrs) = @_;
236 return $self->search_related($rel)->new($values, $attrs);
239 =head2 create_related
241 my $new_obj = $obj->create_related('relname', \%col_data);
243 Creates a new item, similarly to new_related, and also inserts the item's data
244 into your storage medium. See the distinction between C<create> and C<new>
245 in L<DBIx::Class::ResultSet> for details.
252 my $obj = $self->search_related($rel)->create(@_);
253 delete $self->{related_resultsets}->{$rel};
259 my $found_item = $obj->find_related('relname', @pri_vals | \%pri_vals);
261 Attempt to find a related object using its primary key or unique constraints.
262 See L<DBIx::Class::ResultSet/find> for details.
269 return $self->search_related($rel)->find(@_);
272 =head2 find_or_new_related
274 my $new_obj = $obj->find_or_new_related('relname', \%col_data);
276 Find an item of a related class. If none exists, instantiate a new item of the
277 related class. The object will not be saved into your storage until you call
278 L<DBIx::Class::Row/insert> on it.
282 sub find_or_new_related {
284 return $self->find_related(@_) || $self->new_related(@_);
287 =head2 find_or_create_related
289 my $new_obj = $obj->find_or_create_related('relname', \%col_data);
291 Find or create an item of a related class. See
292 L<DBIx::Class::ResultSet/find_or_create> for details.
296 sub find_or_create_related {
298 my $obj = $self->find_related(@_);
299 return (defined($obj) ? $obj : $self->create_related(@_));
302 =head2 update_or_create_related
304 my $updated_item = $obj->update_or_create_related('relname', \%col_data, \%attrs?);
306 Update or create an item of a related class. See
307 L<DBIx::Class::ResultSet/update_or_create> for details.
311 sub update_or_create_related {
314 return $self->related_resultset($rel)->update_or_create(@_);
317 =head2 set_from_related
319 $book->set_from_related('author', $author_obj);
320 $book->author($author_obj); ## same thing
322 Set column values on the current object, using related values from the given
323 related object. This is used to associate previously separate objects, for
324 example, to set the correct author for a book, find the Author object, then
325 call set_from_related on the book.
327 This is called internally when you pass existing objects as values to
328 L<DBIx::Class::ResultSet/create>, or pass an object to a belongs_to acessor.
330 The columns are only set in the local copy of the object, call L</update> to
331 set them in the storage.
335 sub set_from_related {
336 my ($self, $rel, $f_obj) = @_;
337 my $rel_obj = $self->relationship_info($rel);
338 $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
339 my $cond = $rel_obj->{cond};
340 $self->throw_exception(
341 "set_from_related can only handle a hash condition; the ".
342 "condition for $rel is of type ".
343 (ref $cond ? ref $cond : 'plain scalar')
344 ) unless ref $cond eq 'HASH';
345 if (defined $f_obj) {
346 my $f_class = $self->result_source->schema->class($rel_obj->{class});
347 $self->throw_exception( "Object $f_obj isn't a ".$f_class )
348 unless Scalar::Util::blessed($f_obj) and $f_obj->isa($f_class);
351 $self->result_source->resolve_condition(
352 $rel_obj->{cond}, $f_obj, $rel));
356 =head2 update_from_related
358 $book->update_from_related('author', $author_obj);
360 The same as L</"set_from_related">, but the changes are immediately updated
365 sub update_from_related {
367 $self->set_from_related(@_);
371 =head2 delete_related
373 $obj->delete_related('relname', $cond, $attrs);
375 Delete any related item subject to the given conditions.
381 my $obj = $self->search_related(@_)->delete;
382 delete $self->{related_resultsets}->{$_[0]};
388 B<Currently only available for C<has_many>, C<many-to-many> and 'multi' type
393 =item Arguments: ($foreign_vals | $obj), $link_vals?
397 my $role = $schema->resultset('Role')->find(1);
398 $actor->add_to_roles($role);
399 # creates a My::DBIC::Schema::ActorRoles linking table row object
401 $actor->add_to_roles({ name => 'lead' }, { salary => 15_000_000 });
402 # creates a new My::DBIC::Schema::Role row object and the linking table
403 # object with an extra column in the link
405 Adds a linking table object for C<$obj> or C<$foreign_vals>. If the first
406 argument is a hash reference, the related object is created first with the
407 column values in the hash. If an object reference is given, just the linking
408 table object is created. In either case, any additional column values for the
409 linking table object can be specified in C<$link_vals>.
413 B<Currently only available for C<many-to-many> relationships.>
417 =item Arguments: (\@hashrefs | \@objs)
421 my $actor = $schema->resultset('Actor')->find(1);
422 my @roles = $schema->resultset('Role')->search({ role =>
423 { '-in' -> ['Fred', 'Barney'] } } );
425 $actor->set_roles(\@roles);
426 # Replaces all of $actor's previous roles with the two named
428 Replace all the related objects with the given reference to a list of
429 objects. This does a C<delete> B<on the link table resultset> to remove the
430 association between the current object and all related objects, then calls
431 C<add_to_$rel> repeatedly to link all the new objects.
433 Note that this means that this method will B<not> delete any objects in the
434 table on the right side of the relation, merely that it will delete the link
437 Due to a mistake in the original implementation of this method, it will also
438 accept a list of objects or hash references. This is B<deprecated> and will be
439 removed in a future version.
441 =head2 remove_from_$rel
443 B<Currently only available for C<many-to-many> relationships.>
447 =item Arguments: $obj
451 my $role = $schema->resultset('Role')->find(1);
452 $actor->remove_from_roles($role);
453 # removes $role's My::DBIC::Schema::ActorRoles linking table row object
455 Removes the link between the current object and the related object. Note that
456 the related object itself won't be deleted unless you call ->delete() on
457 it. This method just removes the link between the two objects.
461 Matt S. Trout <mst@shadowcatsystems.co.uk>
465 You may distribute this code under the same terms as Perl itself.