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.
105 =item is_foreign_key_constraint
107 If you are using L<SQL::Translator> to create SQL for you and you find that it
108 is creating constraints where it shouldn't, or not creating them where it
109 should, set this attribute to a true or false value to override the detection
110 of when to create constraints.
114 Tells L<SQL::Translator> that the foreign key constraint it creates should be
115 deferrable. In other words, the user may request that the constraint be ignored
116 until the end of the transaction. Currently, only the PostgreSQL producer
117 actually supports this.
121 Tells L<SQL::Translator> to add an index for this constraint. Can also be
122 specified globally in the args to L<DBIx::Class::Schema/deploy> or
123 L<DBIx::Class::Schema/create_ddl_dir>. Default is on, set to 0 to disable.
127 =head2 register_relationship
131 =item Arguments: $relname, $rel_info
135 Registers a relationship on the class. This is called internally by
136 DBIx::Class::ResultSourceProxy to set up Accessors and Proxies.
140 sub register_relationship { }
142 =head2 related_resultset
146 =item Arguments: $relationship_name
148 =item Return Value: $related_resultset
152 $rs = $cd->related_resultset('artist');
154 Returns a L<DBIx::Class::ResultSet> for the relationship named
159 sub related_resultset {
161 $self->throw_exception("Can't call *_related as class methods")
164 my $rel_obj = $self->relationship_info($rel);
165 $self->throw_exception( "No such relationship ${rel}" )
168 return $self->{related_resultsets}{$rel} ||= do {
169 my $attrs = (@_ > 1 && ref $_[$#_] eq 'HASH' ? pop(@_) : {});
170 $attrs = { %{$rel_obj->{attrs} || {}}, %$attrs };
172 $self->throw_exception( "Invalid query: @_" )
173 if (@_ > 1 && (@_ % 2 == 1));
174 my $query = ((@_ > 1) ? {@_} : shift);
176 my $cond = $self->result_source->resolve_condition(
177 $rel_obj->{cond}, $rel, $self
179 if (ref $cond eq 'ARRAY') {
180 $cond = [ map { my $hash;
181 foreach my $key (keys %$_) {
182 my $newkey = $key =~ /\./ ? "me.$key" : $key;
183 $hash->{$newkey} = $_->{$key};
186 foreach my $key (grep { ! /\./ } keys %$cond) {
187 $cond->{"me.$key"} = delete $cond->{$key};
190 $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
191 $self->result_source->related_source($rel)->resultset->search(
197 =head2 search_related
199 @objects = $rs->search_related('relname', $cond, $attrs);
200 $objects_rs = $rs->search_related('relname', $cond, $attrs);
202 Run a search on a related resultset. The search will be restricted to the
203 item or items represented by the L<DBIx::Class::ResultSet> it was called
204 upon. This method can be called on a ResultSet, a Row or a ResultSource class.
209 return shift->related_resultset(shift)->search(@_);
212 =head2 search_related_rs
214 ( $objects_rs ) = $rs->search_related_rs('relname', $cond, $attrs);
216 This method works exactly the same as search_related, except that
217 it guarantees a restultset, even in list context.
221 sub search_related_rs {
222 return shift->related_resultset(shift)->search_rs(@_);
227 $obj->count_related('relname', $cond, $attrs);
229 Returns the count of all the items in the related resultset, restricted by the
230 current item or where conditions. Can be called on a
231 L<DBIx::Class::Manual::Glossary/"ResultSet"> or a
232 L<DBIx::Class::Manual::Glossary/"Row"> object.
238 return $self->search_related(@_)->count;
243 my $new_obj = $obj->new_related('relname', \%col_data);
245 Create a new item of the related foreign class. If called on a
246 L<Row|DBIx::Class::Manual::Glossary/"Row"> object, it will magically
247 set any foreign key columns of the new object to the related primary
248 key columns of the source object for you. The newly created item will
249 not be saved into your storage until you call L<DBIx::Class::Row/insert>
255 my ($self, $rel, $values, $attrs) = @_;
256 return $self->search_related($rel)->new($values, $attrs);
259 =head2 create_related
261 my $new_obj = $obj->create_related('relname', \%col_data);
263 Creates a new item, similarly to new_related, and also inserts the item's data
264 into your storage medium. See the distinction between C<create> and C<new>
265 in L<DBIx::Class::ResultSet> for details.
272 my $obj = $self->search_related($rel)->create(@_);
273 delete $self->{related_resultsets}->{$rel};
279 my $found_item = $obj->find_related('relname', @pri_vals | \%pri_vals);
281 Attempt to find a related object using its primary key or unique constraints.
282 See L<DBIx::Class::ResultSet/find> for details.
289 return $self->search_related($rel)->find(@_);
292 =head2 find_or_new_related
294 my $new_obj = $obj->find_or_new_related('relname', \%col_data);
296 Find an item of a related class. If none exists, instantiate a new item of the
297 related class. The object will not be saved into your storage until you call
298 L<DBIx::Class::Row/insert> on it.
302 sub find_or_new_related {
304 my $obj = $self->find_related(@_);
305 return defined $obj ? $obj : $self->new_related(@_);
308 =head2 find_or_create_related
310 my $new_obj = $obj->find_or_create_related('relname', \%col_data);
312 Find or create an item of a related class. See
313 L<DBIx::Class::ResultSet/find_or_create> for details.
317 sub find_or_create_related {
319 my $obj = $self->find_related(@_);
320 return (defined($obj) ? $obj : $self->create_related(@_));
323 =head2 update_or_create_related
325 my $updated_item = $obj->update_or_create_related('relname', \%col_data, \%attrs?);
327 Update or create an item of a related class. See
328 L<DBIx::Class::ResultSet/update_or_create> for details.
332 sub update_or_create_related {
335 return $self->related_resultset($rel)->update_or_create(@_);
338 =head2 set_from_related
340 $book->set_from_related('author', $author_obj);
341 $book->author($author_obj); ## same thing
343 Set column values on the current object, using related values from the given
344 related object. This is used to associate previously separate objects, for
345 example, to set the correct author for a book, find the Author object, then
346 call set_from_related on the book.
348 This is called internally when you pass existing objects as values to
349 L<DBIx::Class::ResultSet/create>, or pass an object to a belongs_to acessor.
351 The columns are only set in the local copy of the object, call L</update> to
352 set them in the storage.
356 sub set_from_related {
357 my ($self, $rel, $f_obj) = @_;
358 my $rel_obj = $self->relationship_info($rel);
359 $self->throw_exception( "No such relationship ${rel}" ) unless $rel_obj;
360 my $cond = $rel_obj->{cond};
361 $self->throw_exception(
362 "set_from_related can only handle a hash condition; the ".
363 "condition for $rel is of type ".
364 (ref $cond ? ref $cond : 'plain scalar')
365 ) unless ref $cond eq 'HASH';
366 if (defined $f_obj) {
367 my $f_class = $self->result_source->schema->class($rel_obj->{class});
368 $self->throw_exception( "Object $f_obj isn't a ".$f_class )
369 unless Scalar::Util::blessed($f_obj) and $f_obj->isa($f_class);
372 $self->result_source->resolve_condition(
373 $rel_obj->{cond}, $f_obj, $rel));
377 =head2 update_from_related
379 $book->update_from_related('author', $author_obj);
381 The same as L</"set_from_related">, but the changes are immediately updated
386 sub update_from_related {
388 $self->set_from_related(@_);
392 =head2 delete_related
394 $obj->delete_related('relname', $cond, $attrs);
396 Delete any related item subject to the given conditions.
402 my $obj = $self->search_related(@_)->delete;
403 delete $self->{related_resultsets}->{$_[0]};
409 B<Currently only available for C<has_many>, C<many-to-many> and 'multi' type
414 =item Arguments: ($foreign_vals | $obj), $link_vals?
418 my $role = $schema->resultset('Role')->find(1);
419 $actor->add_to_roles($role);
420 # creates a My::DBIC::Schema::ActorRoles linking table row object
422 $actor->add_to_roles({ name => 'lead' }, { salary => 15_000_000 });
423 # creates a new My::DBIC::Schema::Role row object and the linking table
424 # object with an extra column in the link
426 Adds a linking table object for C<$obj> or C<$foreign_vals>. If the first
427 argument is a hash reference, the related object is created first with the
428 column values in the hash. If an object reference is given, just the linking
429 table object is created. In either case, any additional column values for the
430 linking table object can be specified in C<$link_vals>.
434 B<Currently only available for C<many-to-many> relationships.>
438 =item Arguments: (\@hashrefs | \@objs)
442 my $actor = $schema->resultset('Actor')->find(1);
443 my @roles = $schema->resultset('Role')->search({ role =>
444 { '-in' => ['Fred', 'Barney'] } } );
446 $actor->set_roles(\@roles);
447 # Replaces all of $actor's previous roles with the two named
449 Replace all the related objects with the given reference to a list of
450 objects. This does a C<delete> B<on the link table resultset> to remove the
451 association between the current object and all related objects, then calls
452 C<add_to_$rel> repeatedly to link all the new objects.
454 Note that this means that this method will B<not> delete any objects in the
455 table on the right side of the relation, merely that it will delete the link
458 Due to a mistake in the original implementation of this method, it will also
459 accept a list of objects or hash references. This is B<deprecated> and will be
460 removed in a future version.
462 =head2 remove_from_$rel
464 B<Currently only available for C<many-to-many> relationships.>
468 =item Arguments: $obj
472 my $role = $schema->resultset('Role')->find(1);
473 $actor->remove_from_roles($role);
474 # removes $role's My::DBIC::Schema::ActorRoles linking table row object
476 Removes the link between the current object and the related object. Note that
477 the related object itself won't be deleted unless you call ->delete() on
478 it. This method just removes the link between the two objects.
482 Matt S. Trout <mst@shadowcatsystems.co.uk>
486 You may distribute this code under the same terms as Perl itself.